1. Chapter 2: The Chemistry of Life
Key Terms

2. Adhesion
the force that holds together the molecules of unlike substances whose surfaces are in contact
With a steam locomotive all the power is concentrated in one machine, and therefore the weight on the drivers available for adhesion is limited.

3. Amino acid
any of a large group of organic acids containing a carboxyl group, COOH, and an amino group, NH
The order of these amino acids influences how the protein works.

4. Atom
The smallest component of an element, characterized by a sharing of the chemical properties of the element and a nucleus with neutrons, protons and electrons.
Some elements only exist in nature in pairs of atoms, including hydrogen, nitrogen, and iodine.

5. Carbohydrate
An organic compound that occurs in living tissues or food and that can be broken down into energy by people or animals.
This energy is obtained especially by the chloroplastids, and part of it is at once devoted to the construction of carbohydrate material, being thus turned from the kinetic to the potential condition.

6. Catalyst
A substance that speeds up the rate of a chemical reaction. Read more at
Diesel oxidation catalysts contain palladium, platinum and aluminum oxide, all of which serve as catalysts to oxidize the hydrocarbons and carbon monoxide with oxygen to form carbon dioxide and water.

7. Chemical reaction
A process, involving the breaking or making of interatomic bonds, in which one or more substances are changed into others.
The machine involves a simple chemical reaction as formic acid is dripped into a solution of sulphuric acid.

8. Cohesion
The force by which the molecules of a substance are held together
The effect of thus alternately forcing high-pressure steam among the sand, and of discharging high-pressure water contained in the sand into the well, is to break up any cohesion of the sand, and to allow all the finer particles in the neighborhood of the orifice to rush out with the water through the wire gauze into the well.

9. Compound
a substance containing two or more elements chemically combined in fixed proportions
The conceptions of "element," "compound" and "mixture" became more precise than they had been hitherto; in an element all the atoms are alike, in a compound all the molecules are alike, in a mixture there are different kinds of molecules.

10. Covalent Bonds
The chemical bond formed between two atoms when they share electrons in pairs, so that each atom provides half the electrons
The electrovalent bond weakens and the covalent bond strengthen between manganese and oxygen due to ion polarization effect, which makes the spinel structure more stable.

11. Electrons
The subatomic particle having a negative charge and orbiting the nucleus.
Carbon has four electrons that it uses to form chemical bonds.

12. Enzyme
Any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions. 
An enzyme in the saliva of the mouth starts the process of breaking down the food.

13. Glycerol
An odorless, colorless, syrupy liquid, CH(OH), prepared by the hydrolysis of fats and oils: it is used as a solvent, skin lotion, food preservative, etc., and in the manufacture of explosives, alkyd resins, etc.
At present, glycerol was used as raw materials to produce more and more types of glycerides, triacetin, glycerin fatty acid ester, oleic acid ester compounds etc are widely used as chemicals.

14. Fatty Acids
Any of a class of aliphatic carboxylic acids, of general formula CnH2n+1COOH, that occur combined with glycerol as animal or vegetable oils and fats. Only those with an even number of carbon atoms are normally found in natural fats.
Diets rich in polyunsaturated fatty acids enhance the phenomenon of adaptive cytoprotection and render the duodenal mucosa more resistant to acid.

15. Hydrogen Bond
A chemical bond consisting of a hydrogen atom between two electronegative atoms (e.g., oxygen or nitrogen) with one side be a covalent bond and the other being an ionic bond. 
The existence of hydrogen bond within or between the molecules of pigment can enhance the perdurability, light fastness and weather resistance.

16. Ionic Bond
A chemical bond in which one atom loses an electron to form a positive ion and the other atom gains to electron to form a negative ion. 
The cohesion between aluminium and the interlayer is resulted from the metallic bond and the cohesion between the enamel and the interlayer is brought about by the ionic bond and covalent bond .

17. Lipid
An oily organic compound insoluble in water but soluble in organic solvents; essential structural component of living cells (along with proteins and carbohydrates). 
Lipid loss occurs as a result of using harsh skin care products and damage from the elements.