This section considers some of the chemistry behind the colour of dyes and how the target material, for example a fibre, influences the method of dyeing and the dye used. A dye in solution is coloured because of the selective absorption of certain wavelengths of light by specific bonds in the molecule.
Cannot travel in vaccum. Sound is energy and it causes vibration, which travels in a medium. So imagine molecules transfering the energy (vibration) from source toward a particular direction. In water molecules are more rigid than in gas. So vibration is transferred faster.
A...is held together by covalent bonds. water molecule: An example of a molecule held together by covalent bonds is ... . water: What does it mean to say a water molecule is âpolarâ? Draw a diagram of water to show the answer: Polar molecules have a positive region â in water it is the two hydrogen atoms. If the atoms in a water molecule are held together by covalent bonds, what type of bond holds multiple molecules together? Hydrogen bonds: How are hydrogen bonds and cohesion related? Hydrogen bonds keep water molecules packed tightly together. Cohesion is when two molecules of the same substance are attracted to each other and they stick together. What causes surface tension? Cohesion â the attraction of water molecules to each other. What is the opposite of cohesion?