1.2.0: Redox Reactions
Learning Objectives
- Define oxidation and reduction
- Determine the valence (charge) of an element.
- Determine which element is being oxidized and which is being reduced in a redox reaction.
Oxidation-Reduction Reactions
Earth’s atmosphere contains about 20% molecular oxygen, O 2 , a chemically reactive gas that plays an essential role in the metabolism of aerobic organisms and in many environmental processes that shape the world. The term oxidation was originally used to describe chemical reactions involving O 2 , but its meaning has evolved to refer to a broad and important reaction class known as oxidation-reduction (redox) reactions . A few examples of such reactions will be used to develop a clear picture of this classification.
Some redox reactions involve the transfer of electrons between reactant species to yield ionic products, such as the reaction between sodium and chlorine to yield sodium chloride:
It is helpful to view the process with regard to each individual reactant, that is, to represent the fate of each reactant in the form of an equation called a half-reaction :
\[\ce{2Na}(s)\rightarrow \ce{2Na+}(s)+\ce{2e-}\]
These equations show that Na atoms lose electrons while Cl atoms (in the Cl 2 molecule) gain electrons , the “ s ” subscripts for the resulting ions signifying they are present in the form of a solid ionic compound. For redox reactions of this sort, the loss and gain of electrons define the complementary processes that occur:
\textbf{oxidation}&=\textrm{loss of electrons}\\
\textbf{reduction}&=\textrm{gain of electrons}
\end{align}\)
Remembering Oxidation and Reduction
It is common to remember the difference between oxidation and reduction using one of two pneumonic devices:
-
"LeO goes GeR"
In Greek Mythology, Leo was a lion (like the zodiac sign). And what do lion's do? Well, they roar but that doesn't really fit, so we go with "Ger".
L oses e lectrons = O xidation
G ains e lectrons = R eduction
Figure \(\PageIndex{4}\): Lion image by Tambako, reused under the Creative Commons Attribution 2.0 Generic license. -
"Oil Rig"
O xidation i s l oss
R eduction i s g ain
Figure \(\PageIndex{5}\): Image by Peter Grima, reused under the Creative Commons Attribution 2.0 Generic license.
In this reaction, then, sodium is oxidized and chlorine undergoes reduction . Viewed from a more active perspective, sodium functions as a reducing agent (reductant) , since it provides electrons to (or reduces) chlorine. Likewise, chlorine functions as an oxidizing agent (oxidant) , as it effectively removes electrons from (oxidizes) sodium.
\textbf{reducing agent}&=\textrm{species that is oxidized}\\
\textbf{oxidizing agent}&=\textrm{species that is reduced}
\end{align}\)
Some redox processes, however, do not involve the transfer of electrons. Consider, for example, a reaction similar to the one yielding NaCl:
The product of this reaction is a covalent compound, so transfer of electrons in the explicit sense is not involved. To clarify the similarity of this reaction to the previous one and permit an unambiguous definition of redox reactions, a property called oxidation number has been defined. The oxidation number (or oxidation state ) of an element in a compound is the charge its atoms would possess if the compound was ionic .
Oxidation-reduction (redox) reactions are those in which one or more elements involved undergo a change in oxidation number. While the vast majority of redox reactions involve changes in oxidation number for two or more elements, a few interesting exceptions to this rule do exist as shown below\). Definitions for the complementary processes of this reaction class are correspondingly revised as shown here:
\textbf{oxidation}&=\textrm{increase in oxidation number}\\
\textbf{reduction}&=\textrm{decrease in oxidation number}
\end{align}\]
Returning to the reactions used to introduce this topic, they may now both be identified as redox processes. In the reaction between sodium and chlorine to yield sodium chloride, sodium is oxidized (its oxidation number increases from 0 in Na to +1 in NaCl) and chlorine is reduced (its oxidation number decreases from 0 in Cl 2 to −1 in NaCl). In the reaction between molecular hydrogen and chlorine, hydrogen is oxidized (its oxidation number increases from 0 in H 2 to +1 in HCl) and chlorine is reduced (its oxidation number decreases from 0 in Cl 2 to −1 in HCl).
Several subclasses of redox reactions are recognized, including combustion reactions in which the reductant (also called a fuel ) and oxidant (often, but not necessarily, molecular oxygen) react vigorously and produce significant amounts of heat, and often light, in the form of a flame. Solid rocket-fuel reactions such as the one depicted below are combustion processes. A typical propellant reaction in which solid aluminum is oxidized by ammonium perchlorate is represented by this equation:
\[\ce{10Al}(s)+\ce{6NH4ClO4}(s)\rightarrow \ce{4Al2O3}(s)+\ce{2AlCl3}(s)+\ce{12H2O}(g)+\ce{3N2}(g)\]
Watch a brief video showing the test firing of a small-scale, prototype, hybrid rocket engine planned for use in the new Space Launch System being developed by NASA. The first engines firing at 3 s (green flame) use a liquid fuel/oxidant mixture, and the second, more powerful engines firing at 4 s (yellow flame) use a solid mixture.
Single-displacement (replacement) reactions are redox reactions in which an ion in solution is displaced (or replaced) via the oxidation of a metallic element. One common example of this type of reaction is the acid oxidation of certain metals:
Metallic elements may also be oxidized by solutions of other metal salts; for example:
This reaction may be observed by placing copper wire in a solution containing a dissolved silver salt. Silver ions in solution are reduced to elemental silver at the surface of the copper wire, and the resulting Cu 2+ ions dissolve in the solution to yield a characteristic blue color (Figure \(\PageIndex{6}\)).
Figure \(\PageIndex{6}\): (a) A copper wire is shown next to a solution containing silver(I) ions. (b) Displacement of dissolved silver ions by copper ions results in (c) accumulation of gray-colored silver metal on the wire and development of a blue color in the solution, due to dissolved copper ions. (credit: modification of work by Mark Ott)
Example \(\PageIndex{3}\): Describing Redox Reactions
Identify which equations represent redox reactions, providing a name for the reaction if appropriate. For those reactions identified as redox, name the oxidant and reductant.
- \(\ce{ZnCO3}(s)\rightarrow \ce{ZnO}(s)+\ce{CO2}(g)\)
- \(\ce{2Ga}(l)+\ce{3Br2}(l)\rightarrow \ce{2GaBr3}(s)\)
- \(\ce{2H2O2}(aq)\rightarrow \ce{2H2O}(l)+\ce{O2}(g)\)
- \(\ce{BaCl2}(aq)+\ce{K2SO4}(aq)\rightarrow \ce{BaSO4}(s)+\ce{2KCl}(aq)\)
- \(\ce{C2H4}(g)+\ce{3O2}(g)\rightarrow \ce{2CO2}(g)+\ce{2H2O}(l)\)
S olution
Redox reactions are identified per definition if one or more elements undergo a change in oxidation number.
- This is not a redox reaction, since oxidation numbers remain unchanged for all elements.
- This is a redox reaction. Gallium is oxidized, its oxidation number increasing from 0 in Ga( l ) to +3 in GaBr 3 ( s ). The reducing agent is Ga( l ). Bromine is reduced, its oxidation number decreasing from 0 in Br 2 ( l ) to −1 in GaBr 3 ( s ). The oxidizing agent is Br 2 ( l ).
- This is a redox reaction. It is a particularly interesting process, as it involves the same element, oxygen, undergoing both oxidation and reduction (a so-called disproportionation reaction) . Oxygen is oxidized, its oxidation number increasing from −1 in H 2 O 2 ( aq ) to 0 in O 2 ( g ). Oxygen is also reduced, its oxidation number decreasing from −1 in H 2 O 2 ( aq ) to −2 in H 2 O( l ). For disproportionation reactions, the same substance functions as an oxidant and a reductant.
- This is not a redox reaction, since oxidation numbers remain unchanged for all elements.
- This is a redox reaction (combustion). Carbon is oxidized, its oxidation number increasing from −2 in C 2 H 4 ( g ) to +4 in CO 2 ( g ). The reducing agent (fuel) is C 2 H 4 ( g ). Oxygen is reduced, its oxidation number decreasing from 0 in O 2 ( g ) to −2 in H 2 O( l ). The oxidizing agent is O 2 ( g ).
Exercise \(\PageIndex{3}\)
This equation describes the production of tin(II) chloride:
Is this a redox reaction? If so, provide a more specific name for the reaction if appropriate, and identify the oxidant and reductant.
Answer
Yes, a single-replacement reaction. Sn( s )is the reductant, HCl( g ) is the oxidant.
Summary
Video \(\PageIndex{1}\):
A summary of redox reactions.
One of your professors was a script editor for this video. Hint: It was Dr. Clark
Redox reactions involve a change in oxidation number for one or more reactant elements. Writing balanced equations for some redox reactions that occur in aqueous solutions is simplified by using a systematic approach called the half-reaction method.
Glossary
- combustion reaction
- vigorous redox reaction producing significant amounts of energy in the form of heat and, sometimes, light
- oxidation
- process in which an element’s oxidation number is increased by loss of electrons
- oxidation-reduction reaction
- (also, redox reaction) reaction involving a change in oxidation number for one or more reactant elements
- oxidation number
- (also, oxidation state) the charge each atom of an element would have in a compound if the compound were ionic
- oxidizing agent
- (also, oxidant) substance that brings about the oxidation of another substance, and in the process becomes reduced
- reduction
- process in which an element’s oxidation number is decreased by gain of electrons
- reducing agent
- (also, reductant) substance that brings about the reduction of another substance, and in the process becomes oxidized
- single-displacement reaction
- (also, replacement) redox reaction involving the oxidation of an elemental substance by an ionic species
Contributors and Attributions
-
Paul Flowers (University of North Carolina - Pembroke), Klaus Theopold (University of Delaware) and Richard Langley (Stephen F. Austin State University) with contributing authors. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at<EMAIL_ADDRESS>).
- Adelaide Clark, Oregon Institute of Technology
- Crash Course Chemistry: Crash Course is a division of Complexly and videos are free to stream for educational purposes.


4.3.3: How the Brain Processes Information to Make Decisions - Reflective and Reactive Systems
-
- Last updated
- Save as PDF
- Jamie Hammond and Western Technical College
- OpenStax
Learning Objectives
- Understand the two systems of decision-making in the brain
The human brain processes information for decision-making using one of two routes: a reflective system and a reactive (or reflexive) system. 2,3 The reflective system is logical, analytical, deliberate, and methodical, while the reactive system is quick, impulsive, and intuitive, relying on emotions or habits to provide cues for what to do next. Research in neuropsychology suggests that the brain can only use one system at a time for processing information [Darlow & Sloman] and that the two systems are directed by different parts of the brain. The prefrontal cortex is more involved in the reflective system, and the basal ganglia and amygdala (more primitive parts of the brain, from an evolutionary perspective) are more involved in the reactive system. 4
Reactive Decision-Making
We tend to assume that the logical, analytical route leads to superior decisions, but whether this is accurate depends on the situation. The quick, intuitive route can be lifesaving; when we suddenly feel intense fear, a fight-or-flight response kicks in that leads to immediate action without methodically weighing all possible options and their consequences. Additionally, experienced managers can often make decisions very quickly because experience or expertise has taught them what to do in a given situation. These managers might not be able to explain the logic behind their decision, and will instead say they just went with their “gut,” or did what “felt” right. Because the manager has faced a similar situation in the past and has figured out how to deal with it, the brain shifts immediately to the quick, intuitive decision-making system. 5
Reflective Decision-Making
The quick route is not always the best decision-making path to take, however. When faced with novel and complex situations, it is better to process available information logically, analytically, and methodically. As a manager, you need to think about whether a situation requires not a fast, “gut” reaction, but some serious thought prior to making a decision. It is especially important to pay attention to your emotions, because strong emotions can make it difficult to process information rationally. Successful managers recognize the effects of emotions and know to wait and address a volatile situation after their emotions have calmed down. Intense emotions—whether positive or negative—tend to pull us toward the quick, reactive route of decision making.  This speaks to the power our emotions exert on our decision-making. Big decisions should generally not be made impulsively, but reflectively.
The Role of Emotions
Being aware of the role emotions play in decision-making does not mean that we should ignore them. Emotions can serve as powerful signals about what we should do, especially in situations with ethical implications. You can read more about this particular type of decision-making in the Ethics in Practice box later in this chapter. Thinking through how we feel about the possible options, and why we feel that way, can greatly enhance our decision-making. 6 Effective decision-making, then, relies on both logic and emotions. For this reason, the concept of emotional intelligence has become popular as a characteristic of effective managers. Emotional intelligence is the ability to recognize, understand, pay attention to, and manage one’s own emotions and the emotions of others. It involves self-awareness and self-regulation—essentially, this is a toggling back and forth between emotions and logic so that we analyze and understand our own emotions and then exert the necessary control to manage them as appropriate for the situation. Emotional intelligence also involves empathy—the ability to understand other peoples’ emotions (and an interest in doing so). Finally, emotional intelligence involves social skills to manage the emotional aspects of relationships with others. Managers who are aware of their own emotions can think through what their emotions mean in a given situation and use that information to guide their decision-making. Managers who are aware of the emotions of others can also utilize that information to help groups function more effectively and engage in better group decision-making. While emotional intelligence seems to come easily to some people, it is something that we can develop and improve on with practice. A model of emotional intelligence is presented in Exhibit 2.2.
Concept Check
- Explain the two systems used by the brain in decision-making.
- What is emotional intelligence, and why is it important for decision-making?
References
2. Peter A. Facione & Noreen C. Facione. 2007. Thinking and Reasoning in Human Decision Making: The Method of Argument and Heuristic Analysis, Millbrae, CA: The California Academic Press.
3. Matthew D. Lieberman. 2003. “Reflexive and reflective judgment processes: A social cognitive neuroscience approach.” In (Eds.) Joseph P. Forgas, Kipling D. Williams, & William von Hippel’s: Social judgments: Implicit and explicit processes, 44-67. Cambridge, UK: Cambridge University Press.
4. Adam L. Darlow & Steven A. Sloman. 2010. “Two systems of reasoning: Architecture and relation to emotion,”WIREs Cognitive Science, 1: 382-392.
5. Malcolm Gladwell. 2005. Blink: The Power of Thinking Without Thinking. New York: Back Bay Books.
6. Jennifer M. George. 2000. “Emotions and leadership: The role of emotional intelligence.”Human Relations, 53, 1027-1055


5: Curvature
General relativity describes gravitation as a curvature of spacetime, with matter acting as the source of the curvature in the same way that electric charge acts as the source of electric fields. Our goal is to arrive at Einstein’s field equations, which relate the local intrinsic curvature to the locally ambient matter in the same way that Gauss’s law relates the local divergence of the electric field to the charge density. The locality of the equations is necessary because relativity has no action at a distance; cause and effect propagate at a maximum velocity of \(c\).
-
- 5.1: Introduction to Curvature
- It is hard to define curvature and it can be tricky to distinguish intrinsic curvature (real), from extrinsic curvature (never produce observable effects). The manifestly intrinsic tensor notation protects us from being misled in this respect. If we can formulate a definition of curvature expressed using only tensors that are expressed without reference to any preordained coordinate system, then we know it is physically observable, and not just a superficial feature of a particular model.
-
- 5.3: The Stress-energy Tensor
- In general, the curvature of spacetime will contain contributions from both tidal forces and local sources, superimposed on one another. To develop the right formulation for the Einstein field equations, we need to eliminate the tidal part. Roughly speaking, we will do this by averaging the sectional curvature over all three of the planes t−x, t−y, and t−z, giving a measure of curvature called the Ricci curvature.
-
- 5.5: Curvature Tensors
- If we want to express curvature as a tensor, it should have even rank. Also, in a coordinate system in which the coordinates have units of distance (they are not angles, for instance, as in spherical coordinates), we expect that the units of curvature will always be inverse distance squared.
-
- 5.6: Some Order-of-magnitude Estimates
- As a general proposition, calculating an order-of-magnitude estimate of a physical effect requires an understanding of 50% of the physics, while an exact calculation requires about 75%. We’ve reached the point where it’s reasonable to attempt a variety of order-of-magnitude estimates.
-
- 5.11: Manifolds (Part 1)
- General relativity doesn’t assume a predefined background metric, and this creates a chicken-and-egg problem. We want to define a metric on some space, but how do we even specify the set of points that make up that space? The usual way to define a set of points would be by their coordinates. For example, in two dimensions we could define the space as the set of all ordered pairs (x, y). This doesn’t work in general relativity, because space is not guaranteed to have this structure.
-
- 5.12: Manifolds (Part 2)
- An alternative way of characterizing an n-manifold is as an object that can locally be described by n real coordinates. That is, any sufficiently small neighborhood is homeomorphic to an open set in the space of real-valued n-tuples of the form (x1, x2, . . . , xn). For example, a closed half-plane is not a 2-manifold because no neighborhood of a point on its edge is homeomorphic to any open set in the Cartesian plane.
-
- 5.13: Units in General Relativity
- Analyzing units, also known as dimensional analysis, is one of the first things we learn in freshman physics. It’s a useful way of checking our math, and it seems as though it ought to be straightforward to extend the technique to relativity. It certainly can be done, but it isn’t quite as trivial as might be imagined, and it leads to some surprising new physical ideas.
Contributors and Attributions
- Benjamin Crowell (Fullerton College). General Relativity is copyrighted with a CC-BY-SA license.
- Thumbnail: The overall geometry of the universe is determined by whether the Omega cosmological parameter is less than, equal to or greater than 1. Shown from top to bottom are a closed universe with positive curvature, a hyperbolic universe with negative curvature and a flat universe with zero curvature. (Public Domain; NASA).


4.3D: Siderophores
- Describe the function and variety of siderophores
Iron is essential for almost all living organisms as it is involved in a wide variety of important metabolic processes. However, iron is not always readily available; therefore, microorganisms use various iron uptake systems to secure sufficient supplies from their surroundings. There is considerable variation in the range of iron transporters and iron sources utilized by different microbial species. Pathogens, in particular, require efficient iron acquisition mechanisms to enable them to compete successfully for iron in the highly iron-restricted environment of the host’s tissues and body fluids.
Siderophores are small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria, fungi, and grasses. Siderophores are amongst the strongest soluble Fe 3+ binding agents known. Iron is essential for almost all life, because of its vital role in processes like respiration and DNA synthesis. However, despite being one of the most abundant elements in the Earth’s crust, the bioavailability of iron in many environments such as the soil or sea is limited by the very low solubility of the Fe 3+ ion. This ion state is the predominant one of iron in aqueous, non-acidic, oxygenated environments, and accumulates in common mineral phases such as iron oxides and hydroxides (the minerals that are responsible for red and yellow soil colours). Hence, it cannot be readily utilized by organisms. Microbes release siderophores to scavenge iron from these mineral phases by formation of soluble Fe 3+ complexes that can be taken up by active transport mechanisms. Many siderophores are nonribosomal peptides, although several are biosynthesised independently.
Siderophores are amongst the strongest binders to Fe 3+ known, with enterobactin being one of the strongest of these. Because of this property, they have attracted interest from medical science in metal chelation therapy, with the siderophore desferrioxamine B gaining widespread use in treatments for iron poisoning and thalassemia.
Iron is tightly bound to proteins such as hemoglobin, transferrin, lactoferrin, and ferritin. There are great evolutionary pressures put on pathogenic bacteria to obtain this metal. For example, the anthrax pathogen Bacillus anthracis releases two siderophores, bacillibactin and petrobactin, to scavenge ferric iron from iron proteins. While bacillibactin has been shown to bind to the immune system protein siderocalin, petrobactin is assumed to evade the immune system and has been shown to be important for virulence in mice.
Besides siderophores, some pathogenic bacteria produce hemophores ( heme binding scavenging proteins) or have receptors that bind directly to iron/heme proteins. In eukaryotes, other strategies to enhance iron solubility and uptake are the acidification of the surrounding (e.g. used by plant roots) or the extracellular reduction of Fe 3+ into the more soluble Fe 2+ ions.
Siderophores usually form a stable, hexadentate, octahedral complex with Fe 3+ preferentially compared to other naturally occurring abundant metal ions, although if there are less than six donor atoms water can also coordinate. The most effective siderophores are those that have three bidentate ligands per molecule, forming a hexadentate complex and causing a smaller entropic change than that caused by chelating a single ferric ion with separate ligands.
Siderophores are usually classified by the ligands used to chelate the ferric iron. The majors groups of siderophores include the catecholates (phenolates), hydroxamates and carboxylates (e.g. derivatives of citric acid). Citric acid can also act as a siderophore. The wide variety of siderophores may be due to evolutionary pressures placed on microbes to produce structurally different siderophores, which cannot be transported by other microbes’ specific active transport systems, or in the case of pathogens deactivated by the host organism.
Key Points
- Siderophores are important for some pathogenic bacteria for their acquisition of iron. Many siderophores are nonribosomal peptides, although several are biosynthesised independently.
- The wide variety of siderophores may be due to evolutionary pressures placed on microbes to produce structurally different siderophores which cannot be transported by other microbes’ specific active transport systems, or in the case of pathogens deactivated by the host organism.
- Microbes release siderophores to scavenge iron from these mineral phases by formation of soluble Fe3+ complexes that can be taken up by active transport mechanisms.
Key Terms
- siderophores : Sidereophores are small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria and fungi, and also grasses. Siderophores are amongst the strongest soluble Fe3+ binding agents known.


1.3: Hybridization of orbitals and 3D structures of simple organic compounds
- Understand sp 3 , sp 2 , and sp hybridization of \(\ce{C}\), \(\ce{N}\), \(\ce{O}\), and halogens in organic compounds.
- Understand bond angels and geometries in simple molecules having sp 3 , sp 2 , and sp hybridization of \(\ce{C}\), \(\ce{N}\), \(\ce{O}\).
- Read an electrostatic potential map of a simple organic molecule and recognize the partially charged regions and the lone pairs.
- Understand free rotation around single and triple bonds but not around double bonds.
Prelude to the hybridization of atomic orbitals
Electron configuration of \(\ce{C}\) atom is: 1s 2 , 2s 2 , 2p x 1 , 2p y 1 , 2p z 0 , where 1s is the core-shell and 2s and 2p are in the valence shell. Since two unpaired electrons are in the valence shell in 2p x 1 , 2p y 1 orbitals, it implies that \(\ce{C}\) should have two bonds in its compound. In reality, \(\ce{C}\) has four bonds, e.g., there are four \(\ce{C-H}\) covalent bonds in methane (\(\ce{CH4}\)). It can be explained by assuming that one electron is promoted from 2s to 2p orbital of \(\ce{C}\), resulting in the electron configuration of 1s 2 , 2s 1 , 2p x 1 , 2p y 1 , 2p z 0 , which allows four bonds. The rationale is that making tow addition bonds releases more energy that more than compensates the energy consumed in promoting an electron from 2s to 2p orbital.
The molecular formula of methane is (\(\ce{CH4}\)), which shows the elemental composition but does not show bonds. The Lewis structure of methane is \(\ce{ {H}-\overset{\overset{\huge{H}}|}{\underset{\underset{\huge{H}} |}{C}}\!-H}\) which shows covalent bonds as lines but does not show the actual geometry of the molecule. The geometry of the methane molecule is tetrahedral. \(\ce{C}\) is at the center of the tetrahedron, and four \(\ce{H}\) atoms at the corners of the tetrahedron as illustrated in Figure \(\PageIndex{1}\) a and b. The four bonds are equal and at 109.5 o from each other.
The geometry of the methane molecule, shown in Figure \(\PageIndex{1}\) a and b, disagrees with the geometry of valence orbitals of \(\ce{C}\) illustrated in Figure \(\PageIndex{1}\) c. The s orbital is a spherical shape with a single phase shown by a single shade, while p orbitals have two lobes of opposite phases along the axis indicated by two different shades. The three p orbitals are perpendicular to each other, each lying along one of the three axes: p x along the x-axis, p y along the y-axis, and p z along the z-axis. Suppose the valence s and the three p orbitals of \(\ce{C}\) were involved in the bonding. In that case, there should have been three bonds from the p orbitals perpendicular to each other and one bond from the s orbital different from the other three at any angle around the \(\ce{C}\) nucleus. This difference between the actual and the expected geometry of \(\ce{CH4}\) molecule is explained by the orbital hybridization concept.
According to the orbital hybridization concept, atomic orbitals can combine and produce an equal number of hybrid orbitals of energy and orientation different from the constituent orbitals. The s and all three, any two, or any one of the p valence orbitals of \(\ce{C}\) can mix and produce four sp 3 , three sp 2 , or two sp hybrid orbitals.
The geometry around \(\ce{C}\) atoms in organic molecules agrees with the geometry of the hybrid orbitals, as described in the following sections.
sp 3 Hybridization of \(\ce{C}\)
sp 3 Hybridization process
The s-orbital has a spherical shape and has a single phase as illustrated in \(\PageIndex{2}\) a. Each p orbital has two lobes lying on a straight line with the nucleus at the center. The two lobes have opposite phases, represented by shades as illustrated in \(\PageIndex{2}\) a. The term phase is about the wave nature of electrons. Waves have crests and troughs that are opposite phases.
When one s and three p orbitals mix, a set of four equal hybrid orbitals, called sp 3 orbitals, is formed as illustrated in \(\PageIndex{2}\) b. An sp 3 orbital has two lobes of opposite phases, a more prominent lobe and a smaller lobe, lying along a straight line with the nucleus between the two lobes. Each sp 3 orbital has one-fourth of s and three-fourths of p orbital character. The sp 3 orbitals are arranged in a tetrahedral geometry around the nucleus, as illustrated in Figure \(\PageIndex{2}\) b. In the case of \(\ce{C}\), the four valence electrons distribute one each in the four sp 3 hybrid orbitals.
Formation of methane (\(\ce{CH4}\)) molecule
Each of the four sp 3 orbitals of \(\ce{C}\) overlaps with one 1s orbital of \(\ce{H}\), making a set of four covalent bonds as illustrated in Figure \(\PageIndex{2}\) c. The bond formed by a head-on overlap of atomic orbitals is called a sigma-bond (\(\sigma\)-bond), which in the present case is called \(\sigma\) sp 3 -s bond. The result is a \(\ce{CH4}\) molecule with all bonds equal in a tetrahedral geometry around \(\ce{C}\), which agrees with the observed geometry, as illustrated in Figure \(\PageIndex{1}\): a. All bonds are equal of 108.70 pm bond length and 109.5 o bond angles in a \(\ce{CH4}\) molecule. Figure \(\PageIndex{3}\) presents an interactive model of \(\ce{CH4}\) molecule for lea
Figure \(\PageIndex{3}\): Interactive model of \(\ce{CH4}\) molecule. The model can be enlarged by two fingers gesturing the touchpad or right-clicking and moving and rotated by swiping one finger in the image area or left click the mouse and moving.
Formation of ethane (\(\ce{CH3CH3}\)) molecule
Carbon can form a chain of carbons by making covalent bonds between carbon atoms. For example, a \(\ce{C}\) overlaps a bigger lobe of one of its sp 3 hybrid orbitals with the bigger lobe of the sp 3 orbital of the second carbon along the axis of the sp 3 orbitals to make a \(\sigma\) sp 3 -sp 3 bond as illustrated in Figure \(\PageIndex{4}\) a. The remaining sp 3 orbitals on each \(\ce{C}\) make \(\sigma\) sp 3 -s bond by overlapping with s orbital of \(\ce{H}\) resulting in an ethane \(\ce{C2H6}\) molecule.
Rotation around a single bond is possible under ambient conditions. Rotation around a \(\ce{C-H}\) bond does not change the shape or orientation of any atom in the molecule. However, rotation around \(\ce{C-C}\) in \(\ce{CH3CH3}\) molecule results in different orientations of \(\ce{H}\) atoms on one \(\ce{C}\) relative to the \(\ce{H}\) atoms on the other \(\ce{C}\), as illustrated in Figure \(\PageIndex{4}\) c. The structures with different orientations of atoms in the same molecule, as a result of rotation around a single bond, are called conformers of each other.
sp 2 Hybridization of \(\ce{C}\)
sp 2 Hybridization process
One s and two p orbitals in a valence shell can mix and produce a set of three equal hybrid orbitals, called sp 2 orbitals, as illustrated in Figure \(\PageIndex{5}\). An sp 2 orbital has one-third s-orbital and two-third p-orbital character. An sp 2 orbital comprises two lobes, a more prominent lobe and a smaller lobe of opposite polarity along a straight line with the nucleus between the two lobes, as in the case of the sp 3 orbital. The three sp 2 are in a plane at 120 o from each other, i.e., a trigonal planer geometry with the nucleus in the middle. One p orbital left out from the hybridization lies perpendicular to the plane of the three sp 2 orbitals.
Formation of ethene (\(\ce{H2C=CH2}\)) molecule
A \(\ce{C}\) can form multiple bonds with a \(\ce{C}\) or a heteroatom. For example, a \(\ce{C}\) overlaps a bigger lobe of one of its sp 2 hybrid orbitals with the bigger lobe of the sp 2 orbital of the second carbon along the axis of the sp 2 orbital to make a \(\sigma\) sp 2 -sp 2 bond as illustrated in Figure \(\PageIndex{5}\)b. The remaining sp 2 orbitals on each \(\ce{C}\) make \(\sigma\) sp 2 -s bond by overlapping with s orbital of \(\ce{H}\). Two p orbitals on adjacent carbons orient themselves parallel and overlap sideways, forming a pi-bond (\(\pi\)-bond). This results in the ethene molecule illustrated in Figure \(\PageIndex{5}\)c.
The \(\pi\)-bond is weaker than a \(\sigma\)-bond because the sideways overall of two parallel p-orbitals making a \(\pi\)-bond is less than the head-one overlap of orbitals making a \(\sigma\)-bond. Therefore, a \(\pi\)-bond is formed only when a \(\sigma\)-bond can not be created. A single bond is always a \(\sigma\)-bond. A \(\pi\)-bond and a \(\sigma\)-bond together, i.e., \(\ce{C=C}\) is called a double bond. A double bond is stronger than a single bond. The \(\pi\)-bond becomes more weak if the p-orbitals constituting it are not parallel because the overly is less between nonparllel p-orbitals than between parallel p-orbitals. Ther is no overall lap between p-orbitals perpendicular to each other, i.e., there is no \(\pi\)-bond when p-orbitals are at 90 o (perpendicular). Therefore, rotation around a double does not happen until the \(\pi\)-bond is broken. There is no free rotation around \(\ce{C=C}\) bond.
Geometry around each carbon in the ethene molecule is trigonal planar and bond angles close to the predicted value of 120 o , as illustrated in Figure \(\PageIndex{5}\)d. All six atoms in the ethene ( \(\ce{CH2CH2}\)) molecule are in the same plane and are locked in this geometry due to no free rotation around the \(\ce{C=C}\) bond.
sp Hybridization of \(\ce{C}\)
sp Hybridization process
One s, and one p orbitals in a valence shell can mix and produce a set of two equal hybrid orbitals, called sp orbitals, as illustrated in Figure \(\PageIndex{6}\)a. An sp-orbital has 50% s-orbital and 50% p-orbital character. Like sp 3 and sp 2 orbitals, an sp orbital comprises two lobes, a more prominent lobe and a smaller lobe of opposite polarity along a straight line with the nucleus between the two lobes. The two sp orbitals are in a line at 180 o from each other, i.e., a linear geometry with the nucleus in the middle. Two p orbitals left out from the hybridization lie perpendicular to the axis of the sp orbitals and perpendicular to each other, as illustrated in Figure \(\PageIndex{6}\)a.
d)
Formation of ethyne (\(\ce{HC#CH}\)) molecule
An sp-hybridized \(\ce{C}\) overlaps a more prominent lobe of one of its sp orbitals with the bigger lobe of sp orbital of the second carbon along the axis of the sp orbitals to make a \(\sigma\) sp-sp bond as illustrated in Figure \(\PageIndex{6}\)b. The remaining sp orbitals on each \(\ce{C}\) make \(\sigma\) sp-s bond by overlapping with s orbital of \(\ce{H}\). One p orbitals on a \(\ce{C}\) orient itself parallel to one p-orbital on the other and overlap sideways, forming a \(\pi\)-bond. The other two p orbitals are also parallel to each other and overlap sideways to form the second \(\pi\)-bond as illustrated in Figure \(\PageIndex{6}\)c. This results in an ethyne molecule with a triple (\(\ce{C#C}\)) bond, i.e., a \(\sigma\)-bond and two \(\pi\)-bonds between the two \(\ce{C}\) atoms, as illustrated in Figure \(\PageIndex{6}\)d.
 Unlike a double bond, rotation around a triple bond happens because as the \(\pi\)-bond starts breaking due to p-orbitals going away from parallel orientation, a new \(\pi\)-bond starts making with the alternate p-orbital on the neighboring \(\ce{C}\). This fact becomes apparent by comparing the \(\pi\)-bond electron clouds in the cases of a double bond of ethene and a triple bond of ethyne illustrated in Figure \(\PageIndex{7}\). However, the rotation around a triple-bond means less as its geometry is linear.
Hybridization of \(\ce{N}\), \(\ce{O}\), and halogens
Heteroatoms like \(\ce{N}\), \(\ce{O}\), and halogen atoms (represented as: \(\ce{X}\)) can also mix all or some of their valence shell s and p orbitals to have sp 3 , sp 2 , or sp hybridization like \(\ce{C}\). The differences are the following.
Number of covalent bonds and lone pairs in compounds
Table 1 shows the number of covalent bonds and the number of lone pairs on atoms of elements commonly found in organic compounds. \(\ce{C}\) has four valence electrons that distribute one each in the hybrid orbitals and the remaining p orbitals. Lewis symbols of elements represent valence electrons around the symbol of the element. For example, Lewis symbol of \(\ce{C}\) is \(\ce{.\overset{\Large{\cdot}}{\underset{\Large{\cdot}}{C}}.}\) that shows four unpaired electrons in the valence shell. Each unpaired valence electron can make one covalent bond. So, \(\ce{C}\) makes four covalent bonds in organic compounds.
\(\ce{H}\) has one valence electron, represented as \(\ce{\!\overset{\Large{\cdot}}{H}}\) that shows one unpaired electron that makes one bond and no lone pair on \(\ce{H}\) in their compounds.
\(\ce{N}\) has five valence electrons represented in Lewis symbol as \(\ce{.\overset{\Large{\cdot}}{\underset{\Large{\cdot\cdot}}{N}}.}\) that shows three unpaired electrons and one electron pair. The unpaired electrons make one bond each while the paired electrons remain as a lone pair on \(\ce{N}\) in its compounds.
\(\ce{O}\) has six valence electrons represented in Lewis symbol as \(\ce{.\overset{\Large{\cdot\cdot}}{\underset{\Large{\cdot\cdot}}{O}}.}\) that shows two unpaired electrons and to electron pairs. The unpaired electrons make one bond each while the paired electrons remain as two lone pairs on \(\ce{O}\) in its compounds.
Halogen \(\ce{X}\) ( where \(\ce{X}\) can be \(\ce{F}\), \(\ce{Cl}\), \(\ce{Br}\), or \(\ce{I}\)) has seven valence electrons. For example, \(\ce{Cl}\) represented as \(\ce{:\!\overset{\Large{\cdot}}{\underset{\Large{\cdot\cdot}}{Cl}}\!:}\) that shows one unpaired electron that makes one bond while the paired electrons remain as three lone pairs on \(\ce{X}\) in their compounds.
| Atom (Lewis symbol) | Number of Covalent bonds | Number of lone pairs |
|---|---|---|
| \(\ce{.\overset{\Large{\cdot}}{\underset{\Large{\cdot}}{C}}.}\) | 4 | 0 |
| \(\ce{\!\overset{\Large{\cdot}}{H}}\) | 1 | 0 |
| \(\ce{.\overset{\Large{\cdot}}{\underset{\Large{\cdot\cdot}}{N}}.}\) | 3 | 1 |
| \(\ce{.\overset{\Large{\cdot\cdot}}{\underset{\Large{\cdot\cdot}}{O}}.}\) | 2 | 2 |
| Halogen \(\ce{:\!\overset{\Large{\cdot}}{\underset{\Large{\cdot\cdot}}{X}}\!:}\) ( where \(\ce{X}\) can be \(\ce{F}\), \(\ce{Cl}\), \(\ce{Br}\), or \(\ce{I}\)) | 1 | 3 |
Geometry around the central atom
sp 3 Hybridization
An sp 3 hybridized \(\ce{C}\) makes four \(\sigma\)-bonds in a tetrahedral geometry around \(\ce{C}\) where bonds are around 109 o from eachother, as illustrated Figure \(\PageIndex{8}\)a for the case of methane (\(\ce{CH4}\)). The electrostatic potential map of methane is also shown.
An electrostatic potential map shows electron cloud in colors: green means neutral or nonpolar region, red means \(\delta{-}\) region, blue means \(\delta {+}\) region, yellow is between neutral and \(\delta{-}\) and light blue is between neutral and \(\delta {+}\).
Methane is nonpolar, shown by green in the electrostatic potential map.
The sp 3 orbitals of \(\ce{N}\) have tetrahedral geometry where three orbitals make \(\sigma\)-bonds while a lone pair occupy the fourth. The three peripheral atoms are at the base forming a triangle while \(\ce{N}\) is raised from the middle of the triangle resulting in a trigonal-pyramidal geometry, as illustrated in Figure \(\PageIndex{8}\)b for \(\ce{NH3}\) molecule. The trigonal-pyramidal geometry is a modified form of tetrahedral geometry where the fourth corner of the tetrahedron is missing due to being occupied by a lone pair. The bond angles are close to 109 o as predicted by the tetrahedral geometry. The molecule is not symmetric with polar bonds, so, it is polar, which is evident from its electrostatic potential map. The red region is due to the polarity of \(\ce{N-H}\) bonds and also due to the lone pair region showing red because it is in an sp 3 -orbital which, unlike a p-orbital, is not symmetric with most of the electron located in the more prominent lobe on one side of the nucleus.
The sp 3 orbitals of \(\ce{O}\) have tetrahedral geometry where two orbitals make \(\sigma\)-bonds while lone pairs occupy the other two. The two corners of a tetrahedron which are peripheral atoms and the \(\ce{O}\) in the middle of the tetrahedron shape, results in a bent shape with the other two corners of the tetrahedron missing due to being occupied by lone pairs as illustrated in Figure \(\PageIndex{8}\)c for \(\ce{H2O}\) molecule. The bent shape is a modified form of tetrahedral geometry where two corners of the tetrahedron are missing due to being occupied by lone pairs. The bond angle is close to 109 o as predicted by the tetrahedral geometry. The electrostatic potential map reflects the polarity of two \(\ce{O-H}\) bonds and the two lone pairs in sp 3 -orbitals.
The sp 3 orbitals of halogen atoms have tetrahedral geometry where one orbital makes a \(\sigma\)-bond while lone pairs occupy the other three. One bond can make only a linear geometry as illustrated in Figure \(\PageIndex{8}\)d for \(\ce{HCl}\) molecule. The other three corners of the tetrahedron are missing due to being occupied by lone pairs. The electrostatic potential map reflects the polarity of the bond and the three lone pairs in sp 3 -orbitals.
b)
d)
sp 2 Hybridization
An sp 2 hybridized \(\ce{C}\) makes three \(\sigma\)-bonds using its sp 2 orbitals in a trigonal planer geometry around \(\ce{C}\) and a \(\pi\)-bond using its p-orbital. The \(\sigma\)-bonds are around 120 o from each other, as illustrated in Figure \(\PageIndex{9}\)a for ethene (\(\ce{H2C=CH2}\)) molecule. The electrostatic potential map of \(\ce{H2C=CH2}\) in Figure \(\PageIndex{9}\)a shows red region around the axis of the \(\ce{C=C}\) bond which is due to the \(\pi\)-bondin electrons placed above and below the \(\sigma\)-bond. Further the \(\ce{H's}\) are bluish compared to those in \(\ce{CH4}\) molecule indicating that the \(\ce{C-H}\) is slightly polar with \(\delta {+}\) charge on the \(\ce{H}\).
The sp 2 orbitals of \(\ce{N}\) have trigonal planer geometry where two of the sp 2 orbitals make \(\sigma\)-bonds, and the lone pair occupies the third sp 2 orbital. The p-orbital makes a \(\pi)-bond. The geometry around an sp 2 hybridized \(\ce{N}\) is bent with a bond angle around 120 o as the trigonal planer geometry predicted. The bent geometry of sp 2 hybridized \(\ce{N}\) is illustrated in Figure \(\PageIndex{9}\)b for methanimine (\(\ce{H2C=NH}\)) molecule. The electrostatic potential map reflects the bond polarity and the lone pair of electrons in one sp 2 -orbital as a red region.
The sp 2 orbitals of \(\ce{O}\) have trigonal planer geometry where one sp 2 orbital makes a \(\sigma\)-bond, and a lone pair occupies the other two sp 2 orbitals. The p-orbital makes a \(\pi)-bond. An sp 2 - hybridized \(\ce{O}\) has a linear geometry around \(\ce{O}\) atom, as illustrated in Figure \(\PageIndex{9}\)c for formaldehyde (\(\ce{H2C=O}\)) molecule. The electrostatic potential map reflects the bond polarity and the lone pair of electrons in two sp 2 -orbitals as a red region.
The sp 2 or hybridization of halogens is not observed except in a few cases, e.g., when one of the lone pairs is involved in resonance which will be described in a later section.
sp Hybridization
An sp hybridized \(\ce{C}\) makes two \(\sigma\)-bonds using its sp-orbitals that are at 180 o from each other, i.e., in a linear geometry. The remaining two p-orbitals make two \(\pi\)-bonds perpendicular to each other and around the sigma bond resulting in a linear geometry around the sp hybridized carbon, as illustrated in Figure \(\PageIndex{10}\)a for ethyne (\(\ce{HC#CH}\)) molecule. Electrostatic map shows red region around the \(\ce{C#C}\) bond axis which is due to \(\pi\)-electrons and it also shows that the \(\ce{C-H}\) bond in ethyne is polar with \(\delta {+}\) charge on \(\ce{H}\)
The sp orbitals of \(\ce{N}\) have linear geometry. One of the sp orbitals makes a \(\sigma\)-bond, and the other is occupied by a lone pair, and the two p-orbital make two \(\pi\)-bonds resulting in a triple bond. The geometry around an sp hybridized \(\ce{N}\) is linear, as illustrated in Figure \(\PageIndex{10}\)b for hydrogen cyanide (\(\ce{HCN}\)) molecule. The electrostatic potential map reflects the bond polarity and shows the red region where the lone pair of electrons are located in an sp-orbital of nitrogen.
The sp hybridization of \(\ce{O}\) is rare in organic compounds, but it does exist, e.g., in carbon monoxide molecule (\(\ce{CO}\)) molecule. It involves formal charges on the atoms, which will be described in a later section.


13.35: Reading- Defining the Message
Why the Message Matters
A clear, consistent message can be the difference between a phenomenally successful marketing campaign and an utter waste of time and money. If you, as a marketer, have not defined your message clearly, how likely is it that your target audiences will get the message you want them to hear? Answer: Not very likely.
With IMC campaigns bringing together multiple communication tools and touch points, the impact of a consistent, effective message is compounded when it reaches the people you’re targeting again and again through different channels. Conversely, in the absence of a clear message, a campaign results in miss after miss after miss in terms of getting your message to your target audience—and it means wasted effort and resources.
The Role of Messaging
In marketing, the term “messaging” refers to how an organization talks about itself and the value it provides. Related to positioning, messaging is an approved set of key points or messages an organization uses to communicate about something with a target audience. Messaging translates a positioning statement into a set of convincing “key message” statements. Marketers use these statements to develop materials for marketing communications such as ad slogans, advertising copy, social media posts, press releases, presentation scripts, and so forth. Messaging documents are a blueprint for what all the other materials–and people–should communicate.
Organizations may create messaging for different purposes. Corporate messaging communicates about the purpose and value a company provides to the market. Brand messaging focuses on how and what to communicate about a company, product, or service brand. Product messaging expresses key selling points about a product. Crisis messaging outlines talking points for how an organization communicates about an unfortunate development, such as a service interruption or a public scandal.
Messaging ensures that everyone in an organization who needs to communicate something with the market can do it with a common set of messages and a common understanding of what the market should hear from them. While messaging is usually created by the marketing team, it may be used by individuals and teams across a company, from executive leaders to product managers, sales representatives and other groups, in addition to the marketing team itself.
Messaging is an essential ingredient for a successful marketing campaign. A campaign may use existing messaging if its goal is tied to a topic for which messaging has already been developed. For example, existing brand messaging might be used to develop a brand-awareness campaign. If no suitable messaging exists, marketers may need to develop key messages expressly for a campaign.
Developing Key Messages
The key messages that make up a messaging document should do the following:
- Express the main idea you want people to understand and remember about your offering
- Resonate with the audience you are targeting, such that they pay attention and feel what you are saying matters
- Articulate clearly and concisely what you need to communicate about: e.g., what you stand for, why you are different, what value you offer, what problems you solve, etc.
The message content, as well as the voice, tone, and style of the message, may vary widely, depending on the organization’s identity and what it wants to accomplish with the communication. All of these elements factor into the key messages and the creation of marketing communication artifacts based on the messaging.
Start with the Basics: What, Who, Why?
Message development starts with doing your homework about what the organization needs to accomplish. Revisit the company goals, objectives, and the marketing strategy to confirm the outcomes that the messaging is designed to help achieve. Consult any related positioning statements the organization has developed, because positioning lays out the foundation for what the organization wants to communicate. As you develop messaging, it’s also a good idea to review any brand-platform content, since that content can help reinforce the organization’s identity, voice, and values.
Next, confirm the audience(s) for the messaging: who are the target segments and stakeholders you need to reach? Some messaging documents outline different sets of key messages for different audiences, depending on what points are most important or convincing for the audience. For example, when company leaders must communicate publicly about poor quarterly earnings, they develop one set of key messages for investors, another set of key messages for employees, and a third set for customers. All these messages are related to one another, but the most important messages for an investor to hear may be different from what employees need to hear.
Identify key words and ideas you want to associate with your organization, product, service, or offering. These words and phrases may figure prominently in the messaging you develop, to help it stand out and differentiate your organization. Also, conduct a competitive messaging analysis to capture what key messages, words, and concepts other organizations are using. Your messaging should avoid sounding like everybody else.
Draft Message Statements
With your audience and objectives in mind, begin drafting key message statements. If you could make only a few key points to your target audience, what would those points be? As you write these message statements, keep the following criteria in mind. Key messages should be:
- Concise: Key message statements should be clear and concise, ideally just one sentence long–but not a long, run-on sentence.
- Simple: Key messages should use language that is easy for target audiences to understand. You should avoid acronyms, jargon, and flowery or bureaucratic-sounding language.
- Strategic: Key messages should differentiate your organization and what you stand for, while articulating the value proposition or key benefits you offer.
- Convincing: Messaging should include believable, meaningful information that creates a sense of urgency and stimulates action. Message wording should be decisive and active, rather than passive.
- Relevant: Key messages should matter to the audience; they should communicate useful, relevant information that the audience finds appealing not only on a logical or rational level but also on an emotional level.
- Memorable: Key messages should stick in the mind, so the impression they make is easy to recall.
- Tailored: Messaging must communicate effectively with intended target audiences. This means the messaging should reflect the target audience’s unique needs, priorities, issues, terminology, relationship to the organization, and other distinguishing factors that might help the messaging better communicate with that audience.
A tip: Don’t worry too much about word-smithing as you develop a first draft of key messages. Get your initial thinking down on paper quickly, and then go back to check against the criteria above as you refine the wording. Remember, you only need a handful of key messages—just one to three well-crafted statements—so don’t slave over trying to fill an entire page.
Organize a Messaging Framework
Once you have drafted an initial set of key messages, it is helpful to prioritize and organize them into a framework that helps you tell a coherent story. Marketers use a variety of different frameworks for this purpose. A simple, standard messaging framework is illustrated in the figure below.
This framework includes key messaging components introduced elsewhere in this course: the brand promise, positioning statement, and target audience. By bringing these elements into the messaging document, it is easy to spot disconnects or confirm alignment between the day-to-day talking points (the primary message and message pillars), the audience, and what the organization stands for (as expressed in the brand promise and positioning statement).
The primary message is sometimes referred to as an elevator pitch . Think of it as the one to three sentences you would say to a member of your target audience if you had just thirty seconds with them in an elevator. In that short time, you need to get across the core ideas. As you review the initial key messages you drafted, identify the most important ideas. Refine them into a concise statement that expresses your primary message.
To support this primary message, identify one to three message pillars that further substantiate the primary message or elevator pitch. When the elevator pitch is expressing a value proposition, the message pillars are usually the key benefits delivered by the value proposition. When the elevator pitch is arguing a position, the message pillars are the key reasons the target audience should believe what is being argued. To identify your message pillars, review the initial messages you drafted. It is likely that your initial work captures some of those pillars or arguments that provide great support for your primary message.
For each message pillar, identify at least three convincing proof points, or reasons the target audience should believe what you tell them. Proof points may come from a variety of sources: actual statistics or data points from research or your customer base; product features and the benefits they deliver; customers’ success stories; and so forth. Their purpose is to provide evidence and add credibility to the messages you want to communicate.
As marketers turn messaging into marketing communication artifacts, the proof points also provide ideas for marketing content: case studies, white papers, advertisement copy, and so forth. They help fill out details around the messaging story you are telling to your target segment(s).
Finally, add a call to action . A call to action is an instruction to the target audience about what you want them to do, once they have heard and digested your messages. Usually it is an imperative verb: Register now . Try this new product. Visit this place. Vote for this person. Although each individual marketing communication piece you create for an IMC campaign might have its own specific call to action, it is helpful to decide on an overarching call to action that identifies the behavioral change you want to incite in your target audience. This call to action serves an important role of making sure that the messages do a good job of convincing the target audience to change their behavior and do what you want them to do. If the messaging doesn’t seem powerful enough to convince people to take action, you need to revisit the messaging and make it more compelling.
The primary purpose of message architecture is to help you make sure that everything you communicate ultimately ties back to the major points you want audiences to know and believe about you. As you finish filling out your message architecture, review it and check for alignment at each level. Each level of the architecture should provide consistency and support for the other levels. If you spot disconnects, work to refine the messaging so there is strong alignment.
Refine Your Work
After completing your message architecture, set it aside for a day or so. Then come back and go through the following checklist. Make revisions and refinements where needed.
- Alignment: Recheck your messaging for alignment. Make sure all levels of the messaging framework are consistent with one another.
- Hearts and Minds: Identify where your messaging is working at a rational level and where it’s working at an emotional level. To be compelling enough to spark a change in behavior, it must appeal to both.
- Strategy: Confirm that the messaging complements your organizational, marketing, and brand strategies. If it isn’t getting you further along those paths, it isn’t doing its job.
- Differentiation: Review your messaging with competitors in mind. Your messaging should set you apart and express messages only you can credibly own. It should be more than just “me, too” catch-up to the competition.
- Tone: When you read your messages out loud, your language should sound natural and conversational. Your messaging should ring true; it should sound like it genuinely comes from your organization and the people who represent you.
- Clarity: If parts of your messaging sound vague or unclear, look for ways to reword them to make them more concise and concrete. People hearing the message should easily understand exactly what you mean.
- Inspiration: Your messaging should motivate and inspire your target audiences to take action. If it isn’t compelling enough to do that, you need to make it stronger.
Once you have completed your messaging framework, test the messages with colleagues and internal stakeholders, as well as with members of your target segment(s). You can do this formally using marketing research techniques, or you can test the messages informally by using them in conversations and gauging whether they produce the desired reaction. Testing helps you figure out quickly what’s working and where there is room for improvement.
Once your messaging framework is complete, you can apply it immediately to marketing campaigns and IMC activity. You should revisit the messaging periodically to make sure it’s still having an impact on your target audiences and helping you achieve your goals.
A Messaging Framework Example
The simple messaging framework shown in Figure 1, above, is easy to use for a variety of different messaging purposes. It can also easily be adapted to include other elements that marketers decide are important to the organization and alignment of messaging.
Let’s take a look at the messaging framework for Highfive, a video conferencing company. The goal of this messaging is to convey the central value proposition of the company and its conferencing product, and it demonstrates good alignment across different components of the messaging. [1]
- Brand Promise: Video conferencing you can actually love
- Positioning Statement: Highfive is the first video conferencing product designed to connect every employee and every conference room in your entire company
- Target Audience: 1, C-level Executive (influencer); 2, Director of IT (buyer); and 3, End-user (user)
- Mission: Our mission is to make every conversation face-to-face
- Tone of Voice: Empowering, progressive, human, and cheeky
- Elevator Pitch: Highfive is video conferencing you can actually love. We believe teams work best face-to-face. That’s why we designed the first video conferencing product designed to connect every person and room in an organization. Highfive provides an all-in-one video conferencing hardware device that plugs into any TV screen, turning any ordinary meeting room into a video room. Highfive also provides cloud apps, which allow employees and guests to simply click a link from any laptop or mobile device and instantly connect face-to-face with anyone, anywhere. The hardware device costs the same as a high-end iPad and the cloud apps are free. We think video shouldn’t be a boardroom luxury. It should be available everywhere.
-
Brand Pillars
-
Easy
- Headline benefits: Highfive is beautifully simple video conferencing you can start or join with a single click.
- Supporting examples: Join calls from your calendar, SMS, or email by clicking a URL, hand off video calls from your personal device to a meeting room TV with a swipe or click—no remote control needed. 5-minute plug and play setup.
-
Everywhere
- Headline Benefits: Twenty conference rooms for the price of one Cisco or Polycom system.
- Supporting Examples: Comparable systems cost, about 15 thousand per room. At the price of an iPad, Highfive can be deployed in every room. Free apps let people stay connected at their desks or on the go.
-
Enterprise
- Headline Benefits: Built for businesses, not social networking.
- Supporting Examples: Must sign up with work email address, domain-based security model, enterprise reliability and security built by the same people that built Google Apps for Business.
-
Easy
In this example, marketers have left out the call to action, but they have introduced other components around which they want strong alignment: the company mission and brand voice. The rather long elevator pitch is well supported by clear, compelling message pillars, and the messaging offers ample proof points in the form of product features that substantiate the messaging claims. The messaging itself offers both rational reasons to believe the message (e.g., “simple conferencing you can start or join with a single click”) and emotional benefits to inspire action (e.g., “video conferencing you can actually love . . .”). Finally, the overall tone of the messaging demonstrates strong alignment with the company’s brand identity.
- “How to Create Brand Messaging That Really Resonates.” Salesforce Pardot, February 2, 2015. https://www.pardot.com/blog/how-to-create-brand-messaging-that-really-resonates/ . ↵
Contributors and Attributions
- Reading: Defining the Message. Authored by : Lumen Learning. License : CC BY: Attribution
- Important Message. Authored by : Patrick Denker. Located at : https://www.flickr.com/photos/pdenker/6001236724/ . License : CC BY: Attribution


9.4: Tachogenerators
An electromechanical generator is a device capable of producing electrical power from mechanical energy, usually the turning of a shaft. When not connected to a load resistance, generators will generate voltage roughly proportional to shaft speed. With precise construction and design, generators can be built to produce very precise voltages for certain ranges of shaft speeds, thus making them well-suited as measurement devices for shaft speed in mechanical equipment. A generator specially designed and constructed for this use is called a tachometer or tachogenerator . Often, the word “tach” (pronounced “tack”) is used rather than the whole word.
By measuring the voltage produced by a tachogenerator, you can easily determine the rotational speed of whatever its mechanically attached to. One of the more common voltage signal ranges used with tachogenerators is 0 to 10 volts. Obviously, since a tachogenerator cannot produce voltage when its not turning, the zero cannot be “live” in this signal standard. Tachogenerators can be purchased with different “full-scale” (10 volt) speeds for different applications. Although a voltage divider could theoretically be used with a tachogenerator to extend the measurable speed range in the 0-10 volt scale, it is not advisable to significantly overspeed a precision instrument like this, or its life will be shortened.
Tachogenerators can also indicate the direction of rotation by the polarity of the output voltage. When a permanent-magnet style DC generator’s rotational direction is reversed, the polarity of its output voltage will switch. In measurement and control systems where directional indication is needed, tachogenerators provide an easy way to determine that.
Tachogenerators are frequently used to measure the speeds of electric motors, engines, and the equipment they power: conveyor belts, machine tools, mixers, fans, etc.


1.9 Multiprocessor and Multicore Systems
MultiProcessor System
Two or more processors or CPUs present in same computer, sharing system bus, memory and I/O is called MultiProcessing System. It allows parallel execution of different processors. These systems are reliable since failure of any single processor does not affect other processors. A quad-processor system can execute four processes at a time while an octa-processor can execute eight processes at a time. The memory and other resources may be shared or distributed among processes.
Advantages :
- Since more than one processor are working at the same time, throughput will get increased.
- More reliable since failure in one CPU does not affect other.
- It needs little complex configuration.
- Parallel processing (more than one process executing at same time) is achieved through MultiProcessing.
Disadvantages :
- It will have more traffic (distances between two will require longer time).
- Throughput may get reduced in shared resources system where one processor using some I/O then another processor has to wait for its turn.
- As more than processors are working at particular instant of time. So, coordination between these is very complex.
Multicore System
A processor that has more than one core is called Multicore Processor while one with single core is called Unicore Processor or Uniprocessor. Nowadays, most of systems have four cores (Quad-core) or eight cores (Octa-core). These cores can individually read and execute program instructions, giving feel like computer system has several processors but in reality, they are cores and not processors. Instructions can be calculation, data transferring instruction, branch instruction, etc. Processor can run instructions on separate cores at same time. This increases overall speed of program execution in system. Thus heat generated by processor gets reduced and increases overall speed of execution.
Multicore systems support MultiThreading and Parallel Computing . Multicore processors are widely used across many application domains, including general-purpose, embedded, network, digital signal processing (DSP), and graphics (GPU). Efficient software algorithms should be used for implementation of cores to achieve higher performance. Software that can run in parallel is preferred because the desire is to achieve parallel execution with the help of multiple cores.
Advantages :
- These cores are usually integrated into single IC (integrated circuit) die, or onto multiple dies but in single chip package. Thus allowing higher Cache Coherency.
- These systems are energy efficient since they allow higher performance at lower energy. A challenge in this, however, is additional overhead of writing parallel code.
- It will have less traffic(cores integrated into single chip and will require less time).
Disadvantages :
- Dual-core processor do not work at twice speed of single processor. They get only 60-80% more speed.
- Some Operating systems are still using single core processor.
- OS compiled for multi-core processor will run slightly slower on single-core processor
Adapted from:
"Difference between MultiCore and MultiProcessor System"
by
Ganeshchowdharysadanala
,
Geeks for Geeks
is licensed under
CC BY-SA 4.0


15.11A: Diagnosing Microbial Diseases
- Compare and contrast the various methods used to diagnose microbial diseases: microbial culture, microscopy, biochemical tests and molecular diagnostics
The process of identifying infectious diseases is complex and requires identification of the agent through direct or indirect means. In regards to many microbial diseases, it is often difficult to diagnose an individual based on clinical presentation. As such, further testing is required. The methods used to diagnose microbial disease include microbial culture, microscopy, biochemical tests, and molecular diagnostics.
Microbial Culture
The first tool in diagnosing microbial disease is microbial cultures. The sample is obtained from the infected individual and tested for the presence of an infectious agent or microbe that is capable of growing in specific media. It is critical to isolate the infectious agent in a pure culture containing only the infectious bacteria. The most common method to isolate individual cells and produce a pure culture is to prepare a streak plate. The streak plate method is a way to physically separate the microbial population, and is done by spreading the inoculate back and forth with an inoculating loop over the solid agar plate. Upon incubation, colonies will arise and single cells will have been isolated from the biomass.
It is established that most pathogenic bacteria can be grown on nutrient agar, and the addition or subtraction of specific nutrients can aid in further identification. The use of microbial cultures is common to help in the clinical identification of pathogenic microbes. However, there are specific classes of microbe that require culture within live animals. The bacteria Mycobacterium leprae is such a microbe, as it can only be cultured in animals.
There are also specific types of infectious agents that require the use of xenodiagnosis to promote growth. The parasite responsible for Chagas disease, Trypanosoma cruzi , requires a vector for diagnosis. For example, an uninfected reduviid bug is used to feed from an individual suspected of having Chagas. Once the blood is taken, the bug will be analyzed for Trypanosoma cruzi growth.
Microscopy
An additional tool utilized for microbial disease diagnosis is microscopy. To ensure proper identification of a pathogen, microscopy, in combination with biochemical staining techniques, is often used to ensure definitive identification. Biochemical staining techniques that are used to aid in identification include stains such as Giemsa, crystal violet, and other stains that help distinguish between gram positive and gram negative.
Biochemical Tests
Biochemical tests are also used to help in microbial disease diagnosis. They will specifically test for metabolic and enzymatic products that an infectious agent may use. Biochemical tests will also test for fermentation products, acids, alcohol or gases that may be products of metabolic pathways.
Molecular Diagnostics
The identification of infectious agents is now often done by using molecular based techniques such as polymerase chase reactions ( PCR ). PCR allows for the identification and testing for nucleic acids which are specific to the infectious agent. The need of an infectious agent to amplify its own nucleic acids to ensure successful infection has allowed us to use PCR to detect the presence of these nucleic acids. In combination with the advances made in genome sequencing, the tools and information needed to establish PCR as the gold-standard for diagnosing microbial disease is present.
LICENSES AND ATTRIBUTIONS
CC LICENSED CONTENT, SHARED PREVIOUSLY
- Curation and Revision. Provided by : Boundless.com. License : CC BY-SA: Attribution-ShareAlike
CC LICENSED CONTENT, SPECIFIC ATTRIBUTION
- Infectious disease. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Infecti...se%23Diagnosis . License : CC BY-SA: Attribution-ShareAlike
- xenodiagnosis. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/xenodiagnosis . License : CC BY-SA: Attribution-ShareAlike
- Microbiological culture. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Microbiological_culture . License : CC BY-SA: Attribution-ShareAlike
- K%2520pneumoniae%2520M%2520morganii%2520providencia%2520styphimuriuma. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:K_...phimuriuma.JPG . License : Public Domain: No Known Copyright
Key Points
- Microbial culture is a technique utilized to help in microbial disease diagnosis and can include nutrient plates, liquid cultures, culture within live animals, and use of a vector as well.
- Microscopy is an additional technique used to identify pathogenic microbes by utilizing specialized stains to help identification and characterization based on specific principes.
- Biochemical tests are used to help identify pathogenic microbes and focus on metabolic or enzymatic products that are specific to microbes based on their metabolic pathways.
Key Terms
- xenodiagnosis : The diagnosis of an infectious disease by exposure to a vector of that disease and performing analysis on the vector for the disease.


5.12: Other Formal Structures in the Classical Style - Minuet Form
A classical minuet movement typically contains a main minuet , followed by a trio, _followed by a _da capo repeat of the main minuet (usually performed without taking the repeats). The movement, then, has a large-scale ABA’ form: minuet–trio–minuet da capo .
Both the main minuet and the trio tend to be small ternary structures. Like the minuet/trio movement itself, the small ternary form follows an ABA’ structure. However, the small ternary structure found in the typical main minuet is of the rounded binary type. That is, while there are three distinct modules—A, B, and A’—they are grouped into two larger sections, each of which is repeated.
The first part in the two-part structure is the first reprise , and the second part is the second reprise , so called because they each repeat. The first reprise contains the A module of the minuet; the second contains the B and the A’ modules.
Each section of the minuet’s (or the trio’s) small ternary form has its own formal function attached to it. The formal function exhibited in the A section is called exposition function; the B section contrasting middle function ; and the A’ section recapitulation function.
Exposition
At the least, the exposition module of the minuet typically contains a primary theme: tight-knit (period, sentence, or hybrid), ending with a PAC, or occasionally a HC. It is common, however, for an exposition to have more complex structure, projecting not just primary theme, but secondary thematic function, transition, and closing. Not all of these functions are necessarily present.
Primary Theme
Expositions always have a primary themes . A prototypical primary theme is (1) tight-knit and (2) ends with a PAC or HC in the tonic key. When an exposition does not modulate, it is understood to exclusively express primary theme function.
Secondary Theme
But if the exposition modulates, the functions of transition , and secondary theme may appear as well. At minimum a secondary theme will close with cadential confirmation (usually a PAC) of the subordinate key. Often, it is looser than the main theme—perhaps expanded or contracted .
Transition
If a phrase contains a [pivot chord modulation][modulation.html] linking the main key to the subordinate key, that phrase is understood to express transition function. (If a new phrase begins immediately in the subordinate key through [direct modulation][modulation.html], there is no transition function.)
Very, very often the transition and the secondary theme are “fused” together (TR==>S) in a single phrase.
Closing Section
Sometimes the secondary theme closes with a PAC and is followed by a closing section .
Contrasting Middle
A contrasting middle section is significantly looser than the exposition. Though it may contain some kind of thematic structure (sentence, primarily), it often does not. Sequences and remote tonal areas are quite typical of the digression section. When doing analysis, your goal should be to identify the melodic/motivic material and understand the tonal structure.
Contrasting middle passages end with a I:HC, creating a harmonic interruption. Commonly, the I:HC is followed by a post-cadential “[standing on the dominant][externalExpansions.html].”
Recapitulation
The definitive characteristics of a minuet’s recapitulation function are (1) the return of the basic idea from the A section at its beginning, (2) the return of the home key at its beginning, and (3) a final PAC in the home key.
A recapitulation typically copies the thematic and phrase-structural features of the exposition, but altering the secondary theme so as to end in tonic. Commonly, the recapitulation expands the exposition’s closing phrase .
Trio
Like the minuet, a trio is typically a rounded or simple binary form. It’s primary job is to establish melodic and harmonic contrast. While contrasting tonally with the main minuet is a central feature of the Trio, Trio’s often simply projection modal contrast. When the tonic stays the same, a major-key main minuet might be contrasted with a Trio marked minore. (The corresponding situation for a minor-key main minuet is a maggiore Trio.)