p. 51, #19-24

19. 

a. carbon: 6 protons, 6 electrons

b. aluminum: 13 protons, 13 electrons

c. lead: 82 protons, 82 electrons

d. chlorine 17 protons, 17 electrons

20. 

a. sulfur: not neutral

b. iron: not neutral

c. silver: neutral

d. iodine: not neutral

21. 

a. anion

b. neutral

c. neutral

d. cation

e. cation

22. 

a. gained two electrons

b. neither

c. neither

d. lost an electron

e. lost two electrons

23.

a. hydrogen with 1 proton and 1 electron: H

b. sodium with 11 protons and 10 electrons: Na+

c. chlorine with 17 protons and 18 electrons: Cl-

d. aluminum with 13 protons and 10 electrons: Al3+

24. 

a. KI: potassium iodine

b. Ca2+ and S2-: CaS: calcium sulfide

c. Fe3+ and Br-: iron bromide (III) or FeBr-3

d. Ba2+ and OH-: Ba+OH: barium hydroxide

e. NH4+ and PO43-: sodium phosphate or (NH4)3 PO4

f. Al3+ and O2-: aluminum oxide AlO+