1. Parts of an Atom Proton, Neutron & Electron Proton (p+)
-located inside nucleus
-mass of 1 a.m.u.
-positive (+) charge

2. Neutron (n)
-located inside nucleus
-mass of 1 a.m.u.
-no charge or neutral
Electron (e-)
-located outside nucleus in “cloud”
-mass of 0 a.m.u.
-a negative (-) charge

3. # n 4 n in Li Li Li Li Atomic Number3 Li
6.941
6.941 Li 3 Li
Atomic Number
-the number of protons in one atom (Li = 3p+)
All atoms are neutral so,
# protons = # electrons (Li = 3e-)
Atomic Mass
-the number of p+ and n (Li = p+ & n)
added together
-is the mass number when rounded (Li = 7 p+ & n)
mass # (n & p+) 7 p+ & n
- atomic # (# p+) - 3 p+
# n n in Li

4. Bohr models e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-
p+ & n in nucleus
e- in energy levels around nucleus
3 energy levels
-1st has up to 2e-
-2nd has up to 8e-
-3rd has up to 8e-
e- e- e- e- e- e- e- e- e- e- e- e- e- e-

5. Bohr Model of Lithium e- e- e- 3 Li
6.941 3 4

6. e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-
Bohr Model of Argon e- e- e- e- 18 Ar
39.948 e- e- e- e- 18 e- e- e- e- e- e- 22 e- e- e- e-