1. Biochemistry Why do we need to know chemistry in biology? All life functions are driven by chemical reactions.

2. A. Levels of Organization Tissue Organ System Organ Organism Cell Organelle Molecule Atom

5. B. Elements 1. Substance made up of only one type of atom. 2. About 25 elements are known to be essential to life. 3. Nitrogen, Carbon, Oxygen, and Hydrogen make up 96% of living matter. 4.Phosphorus, sulfur, calcium, potassium, and a few others make up the remaining 4%.

7. 5. Trace Elements: required by organisms in minute amounts Ex: Iron – all organisms Iodine – vertebrates 6. Some very important elements to become familiarized with include: C, H, O, N, S, P, Mg, Ca, Na, Cl, K, I, Al, Fe

8. C. The Atom 1. smallest unit of matter that retains the properties of an element ChargeMassLocation Protons Neutron Electrons 2. Subatomic Parts: 1.7 x 10 -24 g ≈ 1 amu 1.7 x 10 -24 g ≈ 1 amu 1/1840 amu Atomic nucleus Orbitals

10. 3.Atoms of different elements differ in their number of subatomic particles a) Atomic Number = the number of protons (and # of electrons  if the atom has a neutral charge). b) Mass Number = sum of protons + neutrons *Used as an approximation of atomic weight

11. Atomic Number # Protons = # Electrons = 4 4 Mass Number # Protons + Neutrons = 9

12. Atomic Number # Protons = # Electrons = 4 4 Mass Number # Protons + Neutrons = 9 *To calculate # of neutrons: Subtract Atomic # from the Mass # 9 - 4 5 # of neutrons

13. atomic number mass number / atomic weight # protons = # electrons = # neutrons = 2 2 2

15. c) Isotopes All atoms of the same element have the same number of protons but can have a different number of neutrons.

16. 4. Electron Orbitals 3-D space in which electrons move around the nucleus a) No more than 2 electrons can occupy a single orbital. b) Orbitals are organized into energy levels that surround the atomic nucleus. *First Level = 1 orbital **Each level After = 4 orbitals c) Valence Electrons: found in the outermost level *chemical properties depend on valence electrons (for chemical bonding)

18. Bohr Diagram: Carbon P: N: 6 6 Nucleus

19. Bohr Diagram: Oxygen P: N: 8 8 Nucleus

20. Bohr Diagram: Sodium P: N: 11 Nucleus

21. Lewis Dot Structure Diagram Only shows atomic symbol and valence electrons *Use periodic table group trick Sodium: Na Aluminum: Al Oxygen: O