Question

consider the lewis electron formulas for the following four
lanthanum has 1 dots and a charge of 2
lanthanum ion has 3 dots and a charge of 4
sulfur has 5 dots and a charge of 6
sulfide ion has 7 dots and a charge of 8
a. -2 b. -4 c. +2 or 2 d. +4 or 4 e. +3 or 3 f. 8 g. 0
h. 6 i. 10

Explanation:

Step1: Determine valence electrons of neutral lanthanum

Lanthanum (La) is in group 3, so neutral La has 3 valence - electrons. In Lewis structure, each dot represents a valence electron, so it has 3 dots and a neutral charge of 0.

Step2: Determine characteristics of lanthanum ion

Lanthanum commonly forms a 3+ ion by losing its 3 valence electrons. So the lanthanum ion has 0 dots and a charge of +3 or 3.

Step3: Determine valence electrons of neutral sulfur

Sulfur (S) is in group 16, so it has 6 valence electrons. In Lewis structure, it has 6 dots and a neutral charge of 0.

Step4: Determine characteristics of sulfide ion

Sulfur gains 2 electrons to form sulfide ion ($S^{2 - }$). It now has a full octet (8 electrons), so 8 dots and a charge of - 2.

Answer:

1. E. +3 or 3
2. G. 0
3. G. 0
4. E. +3 or 3
5. H. 6
6. G. 0
7. F. 8
8. A. - 2