# Quiz | Ionic Bonds and Compounds

1

Which group typically forms ions with a +2 charge?

Alkali metals

Alkali earth metals

Chalcogens

Halogens

Octet rule: Atoms tend to reach an octet in the valence shell and attain a noble-gas configuration

Alkali earth metals (second column in the periodic table) need to lose 2 electrons to attain the nearest noble-gas configuration

2

Which of the following compounds would you expect to be ionic?

NH3

SF6

CaO

H2O

Ionic bonds form between a metal and a nonmetal while covalent bonds form between two nonmetals

3

What is the formula of the compound formed between magnesium and nitrogen ions?

MgN

MgN2

Mg2N3

Mg3N2

In order to follow the octet rule: Mg must lose 2 electrons ⇒ Mg2+  and  N must gain 3 electrons ⇒ N3-

4

Which one of the following compounds is chromium (III) oxide?

CrO3

Cr3O

Cr2O3

Cr3O2

Chromium (III) = Cr3+, Oxide = O2-

5

What is the energy of the formation of O2- (g) starting from O (g)?

Coulomb energy of O2-

First electron affinity + second electron affinity of oxygen

Second electron affinity of oxygen

Second ionization of oxygen

O (g) + 1 e- $\to$ O- (g)

O- (g) + 1 e- $\to$ O2- (g)

electron affinity = change in energy when an electron is added to the atom to form an anion

6

How is generally the formation of ionic compounds?

Exothermic

Endothermic

It depends on the starting material

It depends on the reaction conditions

Ionic bond energy = ionization energy (endothermic) + electron affinity (exothermic) + Coulomb energy (exothermic)