1. Atomic Structure

2. Atomic number – number of protons Mass number – number of protons + neutrons Protons (+)electrons (-) Neutrons (neutral) Energy levels contain electrons: 1st = 2 2 nd = 8 3 rd = 18

3. Chemical symbol - always printed, never in script - Capital and lower case matter Co = cobalt CO = carbon monoxide

4. Periodic table – elements are arranged by atomic number

5. Chemical formula – how many of which atom are in a molecule coefficient = number of molecules subscript = number of atoms 2H 2 O = 2 water molecules, with 2 hydrogen atoms and 1 oxygen in each

6. Sodium: Atomic #11 Mass #23 P = 11 N = 12 E = 11