2SAS pg. 131 #13-25

13)
a. Periods
b. Groups or Families

14)
1. Sodium (Na)
2. Potassium (K)

15)
a. The noble gases are located in the rightmost column
b. All nobles gases are unreactive
c. They all have low melting and boiling points

16)
a. MgF₂
b. GaP
w 17)
98+39=137
137/2=68.568.5°C

18) I would expect Chlorine's boiling point to be lower than Iodine's because Iodine has a larger atomic weight.

19)
a. Carbon 
b. Nitrogen
c. 20
d. 20
e. Platinum
f. 78
g. 92
h. 92

20)
a. 4 protons, 4 electron, 5 nuetrons
b. 7 protons, 7 electrons, 7 nuetrons
c. 10 protons, 10 electrons, 10 nuetrons

21) The correction is that Pb has lost 2 electrons. 

22) 
a. 
Carbon: 12
Nitrogen: 14
Calcium: 40
Platinum: 195
Uranium: 238
b. Carbon 

23) No there is not enough information since we don't the atomic weight or atomic numbe.

24) The mass of an electron is 1/2000 of a proton or nuetron.

25) 
24: 12, 12
25: 12, 13
26: 12, 14