Question

1. what is the charge of a potassium ion?

a) +1 b) -1 c) -2 d) +2

1. what is the charge of the oxide ion?

a) +1 b) -1 c) -2 d) +2

1. the total positive and negative charges in an ionic compound must equal

a) one b) zero c) any number

1. in the name iron (iii) ion, the roman numeral iii means

• 3- is the charge
• iron is an anion
• iron is sharing electrons
• 3+ is the charge

1. when atoms satisfy the octet rule, they

• have 8 valence electrons
• have 4 electrons total
• have 6 valence electrons

1. which of the following is a covalent compound?

nacl
so₂
cao
kbr

1. which of the following is an ionic compound?

h₂o
n₂
cacl₂
co₂

1. s²⁻ has the same number of electrons as which noble gas?

ar
ne
he

1. what is the symbol for the hydroxide ion?

(nh₄)⁺
(oh)⁻
(no₃)⁻
(so₄)²⁻

Explanation:

7. Potassium (Group 1) loses 1 electron, forming +1 ion.

8. Oxygen (Group 16) gains 2 electrons, forming -2 ion.

9. Ionic compounds are neutral, so total charges sum to 0.

10. Roman numerals in ion names indicate positive charge.

11. Octet rule means 8 valence electrons for stability.

12. Covalent compounds form between nonmetals; SO₂ has S and O (nonmetals).

13. Ionic compounds form between metal and nonmetal; CaCl₂ has Ca (metal) and Cl (nonmetal).

14. Sulfur (16 electrons) gains 2 to make 18, same as Ar (18 electrons).

15. Hydroxide ion is a combination of oxygen and hydrogen with -1 charge.

Answer:

1. a) +1
2. c) -2
3. b) zero
4. 3+ is the charge
5. have 8 valence electrons
6. SO₂
7. CaCl₂
8. Ar
9. (OH)⁻