CHAPTER 2: THE CHEMISTRY OF LIFE

OBJECTIVE OF CHAPTER:

To understand how chemistry, certain elements, and compounds can have an effect on life.

MAJOR AREAS OF STUDY

I. Structure of Atoms

II. Elements and Compounds

III. Chemical Bonds

IV. Water and its properties

V. Acids and Bases

VI. Chemistry of Carbon

VII. Chemical Reactions

CHAPTER OUTLINE

I. Structure of AtomsA. Protons

(a) Positive Charge

(b) Located in Nucleus

B. Neutrons

(a) No Charge

(b) Found in Nucleus

C. Electrons

(a) Negative Charge

(b) Located outside the Nucleus

Atoms are neutrally charged, contain same number of protons and electrons

Atomic number: number of protons in an atom

Mass number: number of protons and neutrons (carry a mass of one) in an atom

II. Elements and CompoundsA. Element: Consist of one type of atom

1. Isotope: Element with a different number of neutrons. Ex. Carbon 14Isotopes have same number of electrons and chemical properties

2. Radioactive Isotopes: Elements with unstable nucleiUsed to determine age, medicine, and kill bacteria

B. Compounds: Chemical combination of 2 or more elements ex. NaCl saltCompounds held together by Chemical Bonds. Chemical bonding involves the electrons (valence electrons)

1. Ionic a. Electrons are transferredb. One element becomes positive and the other negative

2. Covalenta. Electrons are sharedb. Compounds in living things

3. Van der Waals ForcesAttraction between positive and

negative forces in covalent compounds

Chemical Bonds 2 Rules:1. When chemical bonds are joined energy

is stored2. When chemical bonds are broken energy

is released.

http://youtu.be/QqjcCvzWwwwsed

IV. Properties of WaterA. Liquid at normal temperatureB. Expands when frozenC. Solid phase is less dense than liquidD. Slight positive and negative endsPolar moleculeE. Creates Hydrogen bonds

Cohesion: attraction between molecules of the same substance

Adhesion: attraction between molecules of different substances (Capillary Action)

F. Solutions and Suspensions1. Mixture: two or more elements or compounds that physically mixed together but not chemically combined.Can be separated by physical means.

a. Solutions: Distributed evenly throughout

Solute: what is being dissolvedSolvent: substance in which solute dissolves in

b. Suspensions: materials which do not dissolve but maybe in small pieces and may float in the solvent

V. Acids and BasesA. Acids

1. pH 7 or below2. greater number of H+ ions thanOH- ions3. sour

tastehttp://youtu.be/QqjcCvzWwww

B. Bases1. pH 7 or above2. greater number of OH- ions3. slippery4. bitter taste

Buffer: weak acids or bases that prevent sharp sudden changes in pH. Used by your body to maintain pH level in blood

VI. Carbon ChemistryCarbon:• Has 4 valence electrons• 4 possible bonding sites• Can bond to P, S, N, O, H• Can bond to other carbon atomsPolymerization: large compounds are built by joining smaller ones together. Monomers→Polymers

Four Groups of Organic CompoundsA. Carbohydrates

1. Made up of carbon, hydrogen, and oxygen2. Used for energy (glucose)3. Glucose simple sugar C6H12O6 called Monosaccharide (glucose,

galactose, fructose)4. Compound sugars are calledPolysaccharide (glycogen, stored in liver, cellulose-plants)

B. Lipids: fats, oils, waxes1. Not soluble in water2. Mostly carbon and hydrogen3. Can be used to store energy4. Part of biological membranes and waterproof coverings5. Steroids are lipids6. Lipids are composed of Fatty Acids and Glycerol7. 2 Types: Saturated: all carbon atoms occupiedUnsaturated: one carbon double

bonded

C. Nucleic Acids1. Contain hydrogen, oxygen, nitrogen,

carbon, phosphorus2. Assembled from nucleotides3. Nucleotides: consist of 3 parts: a 5-carbon sugar, phosphate group, and a nitrogenous base. Joined by a covalent

bond4. Nucleotides: Store and transmit

hereditary or genetic information2 Types:DNA: deoxyribonucleic acid (deoxyribose)RNA: ribonucleic acid (ribose)

DNA contains: Adenine, Guanine, Cytosine, ThymineRNA contains: Adenine, Guanine, Cytosine, Uracil

D. Proteins1. Contain nitrogen, carbon, hydrogen,oxygen2. Made of units known as amino acids3. Contains amino group NH-

2 and carboxyl group COOH-

4. Proteins control rate of reactions, regulate cell processes, form bones and muscles, transport, fight disease

VII. Chemical Reactions• Process that changes or transforms one set

of chemicals into another• Made up of Reactants and Products• Exothermic Reactions: release energy or

heat• Endothermic Reactions: absorb energy or

heat

1. Activation Energy: energy needed to start a reaction

2. Enzymesa. Catalyst: substances that speed up the rate of chemical reactions. Lowers the activation energy b. Enzymes affected by pH and

temperaturec. Enzymes provide a site where

reactions can occur. Reactants are called substrates.