Fast heart rate: Tachycardia means fast heart beat. Sinus node is the structure where normally heart rhythm and beat is originated, and it naturally responds to stimuli when the heart needs to beat faster. Inappropriate sinus tachycardia is when the heart is beating fast, when it shouldn't. ...Read more.
The atom is the smallest subdivision of an element which still retains the properties of that element. In fact, a very good definition of an atom is: the smallest part of an element that can enter into a chemical combination. There are around 118 elements known to man, of which 20-30 are really, really important.he parallel definition (to the element one above) for the molecule is: the smallest part of a compound that can enter into a chemical combination. Another definition, equally good, is that a molecule is the smallest stable part of a compound. Water is a typical example of a compound.
From Wikipedia, the free encyclopedia. Chemical composition refers to the arrangement, type and ratio of atoms in molecules of chemical substances. Chemical composition varies when chemicals are added or subtracted from a substance, when the ratio of substances changes, or when other chemical changes occur in chemicals.The chemical composition of a substance determines the properties of the substance.This means that the way atoms are put together in something determines the color, density, strength, and other properties of the thing. This short article about chemistry can be made longer. You can help Wikipedia by adding to it.he chemical composition of a substance determines the properties of the substance. This means that the way atoms are put together in something determines the color, density, strength, and other properties of the thing. This short article about chemistry can be made longer. You can help Wikipedia by adding to it.