Chapter 2 The Chemistry of Life

atom I. atom-smallest part of an element.

A. Made up of: 1. Nucleus Protons (+) Neutrons (neutral)

a. Protons’ mass = neutron mass 2. Electrons (e-) (-) a. Move around nucleus orbitals b. Move in cloudy pathway called orbitals.

c. Much smaller than a proton or neutron d. Same # as protons e. (+) charge of nucleus holds the (-) e- in their orbitals.

Element B. Element- pure substance that consists entirely of one type of atom. 6 C Carbon

1. The difference between atoms of different elements is the # of protons and electrons it has.

Isotopes 2. Isotopes- atoms of the same element that have a different number of neutrons. Radioactive isotope a. Radioactive isotope- isotopes that have an unstable nucleus.

6 electrons 6 protons 8 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 6 neutrons Nonradioactive carbon-12Nonradioactive carbon-13Radioactive carbon-14

i. Used to determine the age of rocks and fossils, treat cancer, kill bacteria, and trace different molecules through organisms.

Chemical bonds II. Chemical bonds-linkbetween atoms A. Make: Compounds 1. Compounds-bonding of at least two different elements.

B. Why do atoms bond to each other? 1. To fill their electron orbitals. Molecule 2. Molecule-two or more atoms joined together by a covalent bond.

C. Types of bonds Covalent bonds 1. Covalent bonds-e- are shared between 2 atoms.

a.Can be: i. Single bond ii. Double bond iii. Triple bond

Ionic bonds 2. Ionic bonds- when e- are lost or gained, then the resulting ions attract. ion a. ion- an atom that has gained or lost e-, therefore acquiring a charge.

Sodium atom (Na)Chlorine atom (Cl)Sodium ion (Na + )Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

Sodium atom (Na)Chlorine atom (Cl)Sodium ion (Na + )Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

Van der Waals forces 3. Van der Waals forces- an attraction between oppositely charged parts of nearby molecules.

D. Chemical formulas 1. Examples: a. H 2 O b. C 6 H 12 O 6 c. CH 4

III. Water A. Properties of water Polar 1. Polar- has a slight positive charge on one end of the molecule, and a slight negative charge on the other end b/c one atom pulls e- closer than the other.

a. O pulls harder than H

2. Forms hydrogen bonds. a. Because of this water has: Cohesion i. Cohesion- attraction between molecules of the same substance. - causes water’s surface tension. m/videos/video.php?v=wshh7j cpeM1fE63Eqwx2

Adhesion b. Adhesion- attraction between molecules of different substances. - causes capillary action (how water gets from the roots to stem and leaves)

3. Water is the universal solvent. a. b/c it’s polar, it pulls apart other molecules (things dissolve in it easily). Solvent b. Solvent- substance in which the solute dissolves.

Solute c. Solute- substance that is dissolved. Solution d. Solution- mixture of two or more substances where each substance is evenly distributed.

Aqueous solution e. Aqueous solution- when something is dissolved in water.

IV. pH scale (ranges from 0-14) A. H 2 0H+ + OH- base C. base- produces OH- ions (>7- 14). acid B. acid- produces H+ ions (0<7).

Buffer D. Buffer- weak acids or bases that react with strong acids or bases to prevent a sudden change in pH.

V. Compounds of Life A. Carbon=most important element in life 1. Why? a. Can form 4 strong covalent bonds.

b. Can form long chains or rings. c. Can form single, double, or triple bonds. MethaneAcetyleneButadieneBenzeneIsooctane

Organic compound 2. Organic compound-any compound that contains carbon. Inorganic compounds 3. Inorganic compounds- any compound that does not contain carbon.

VI. Macromolecules Monomer 1. Monomer- small molecule that makes up polymers. Polymer 2. Polymer- large molecules made of smaller molecules (monomers).

Macromolecule 3. Macromolecule- large polymers. A. Four major classes of macromolecules (Carbohydrates, Lipids, Proteins, Nucleic Acids)

a. Living things use them as their main source of energy. Carbohydrates 1. Carbohydrates- made of carbon, hydrogen,and oxygen.

b. Include sugars (monomers) and starches (polymers) c. Simple sugars (glucose & fructose) = C 6 H 12 O 6 monosaccharides i. Simple sugars are also called monosaccharides.

d. Organisms store simple sugars by linking them into polymers. polysaccharides i. These polymers are called polysaccharides.

ii. In plants = starch iii. In animals = glycogen

Lipids 2. Lipids- are made mostly of carbon and hydrogen and includes waxes, fats, & oils. a. Lipids are used to store energy. b. Lipids are an important part of biological membranes.

c. Lipids are made of glycerol and fatty acids (monomers).

b. Two kinds of fats: Saturated fat i. Saturated fat- fatty acids have the max # of H’s

Unsaturated fats ii. Unsaturated fats- fatty acids don’t have maximum # of H’s.

Nucleic acids 3. Nucleic acids- polymers assembled from individual monomers called nucleotides. a. Nucleic acids store and transmit heredity or genetic information.

b. Two kinds of nucleic acids: i. DNA (Deoxyribonucleic acid) ii. RNA (Ribonucleic acid)

b. Each nucleotide (monomer of nucleic acids) is made up of: i. 5-carbon sugar (Ribose in RNA and Deoxyribose in DNA) ii. Phosphate group iii. Nitrogenous base

Proteins 3. Proteins- polymers of molecules of amino acids. a. There are 20 different amino acids. b. Each amino acid has an amino group (NH 2 ) and a carboxyl group (COOH) at the end.

General structureAlanineSerine Amino group Carboxyl group

c. Each also has an “R” group that is different for every amino acid. d. When two amino acids bond, the COOH bonds to the NH 2 to form a peptide bond and water (H 2 O).

polypeptide e. polypeptide- (another name for protein) several amino acids bound together f. The instructions for arranging a protein are in the DNA.

12 3 4

g. Proteins have many functions including: i. Providing structure (making muscle, bone, etc.) ii. Transport substances in and out of the cell. iii. Fight off diseases.

iv. Control the rate of chemical reactions and regulate cell processes.

Chemical Reaction V. Chemical Reaction- process that changes one set of chemicals into another set. A. Your body uses chemical reactions everyday.

C. ex: CO 2 + H 2 0 H 2 CO 3 Reactants Products B. Chemical reactions always involve breaking bonds and making new bonds.

D. Energy is released when chemical bonds are broken; energy is stored when chemical bonds are made.

Activation energy E. Activation energy- energy that’s needed to get a reaction started. Catalyst 1. Catalyst- molecule that speeds up a chemical reaction.

Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants

Enzyme 2. Enzyme- protein catalyst in living things. a. An enzyme lowers the amount of activation energy it takes to start a reaction.

Glucose Substrates ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products Glucose-6- phosphate Products are released Active site

b. Factors that can affect how an enzyme works: i. Temperature ii. pH