1. Ch 2-Chemistry of Life Atom-basic unit of matter – Very small – Made up of subatomic particles Protons-positively charged particles Neutrons- carry no charge – Protons and neutrons have about the same mass Electrons- negatively charged particle – 1/1840 the mass of proton

2. Element- pure substance that consists entirely of one type of atom – What does atomic number stand for? Atomic mass? Isotope- atoms of an element can have different numbers of neutrons – Have same chemical properties of element – Radioactive isotopes-nuclei are unstable and break down at constant rate over time How are radioactive isotopes useful? Compound- a substance formed by the chemical combination of 2 or more elements – Chemical formula – CO₂, H₂O

3. Chemical bonds- forces that hold atoms together in compounds Main types of bonds-ionic and covalent Ionic bond- one or more electrons are transferred from one atom to another – Ions-positively and negatively charged atoms Covalent bond- electrons are shared between atoms – May be single, double or triple bonds Molecules-smallest unit of most compounds

4. Sec 2-Properties of Water Polar molecule-molecule in which charges are unevenly distributed Water molecule is polar-there is uneven distribution of electrons between oxygen and hydrogen atoms – Negative pole near oxygen, positive pole near hydrogen atoms Hydrogen bonds-form between hydrogen atom on one water molecule and oxygen atom of another water molecule – Weaker bond – Responsible for many special properties

5. Single water molecule may have 4 hydrogen bonds at one time Cohesion-attraction between molecules of same substance Adhesion-attraction between molecules of different substances – Capillary action Mixture- material composed of two or more elements or compounds, physically mixed together, not chemically combined Solutions- type of mixture in which all components are evenly distributed throughout

6. Acids and Bases pH scale- indicates the H₊ ions in a solution – Ranges from 0-14 Acids- any compound that forms H₊ ions in solution Bases- compound that produces hydroxide ions (OH-) in solution pH of fluids in most cells in humans (6.5-7.5). If lower or higher could affect chemical reactions – The body controls this with buffers-weak acids or bases, react with strong acids and bases to prevent sudden changes in pH

7. Sec 3-Carbon Compounds Carbon has ability to form millions of different large and complex structures Macromolecules-large compounds, made up of smaller molecules formed through polymerization – Monomers-smaller units that form polymers-large units Groups of organic compounds found in living things – Carbohydrates, lipids, nucleic acids, proteins

8. Carbohydrates Compounds made up of C, H, O. Usually in a 1:2:1 ratio Main source of energy Used for structural proteins by plants and some animals Monosaccharides-single sugar molecules – Glucose, galactose, fructose Polysaccharides- large macromolecules formed from monosaccharides – Glycogen, Cellulose

9. Lipids Made of mostly C, H Fats, oils, waxes, steroids Store energy, important parts of biological membranes and waterproof coverings Saturated-fatty acids contain max number of hydrogen atoms Unsaturated- at least one carbon-carbon double bond in fatty acid. More than one bond=polyunsaturated – Tend to be liquid at room temp, olive oil – Poly=corn, sesame, canola, peanut

10. Nucleic Acids Macromolecule that contain H, O, N, C, P Nucleotides- made up of 5-carbon sugar, phosphate group, a nitrogenous base Store and transmit hereditary or genetic information – Deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) – What’s the difference?

11. Proteins Macromolecules that contain N, C, H, and O Are made up of chains of amino acids 20 different amino acids occur in nature Control the rate of reactions and regulate cell processes Used to form bones and muscles Transport substances into and out of cells Help fight disease

12. Sec 4- Chemical Reactions and Enzymes Chemical reaction-process that changes, or transforms, one set of chemicals into another – Reactants and products Always involve changes in the chemical bonds that join atoms in compounds CO₂+ H₂O→ H₂CO₃ H₂CO₃→ CO₂+ H₂O

13. Enzymes Catalyst- a substance that speeds up the rate of a chemical reaction – Work by lowering reaction’s activation energy- energy needed to get reaction started Enzymes- proteins that act as biological catalysts – Speed up chemical reactions that take place in cells – Lowers activation energy