Question

Label the following hydrides as ionic, covalent, or interstitial, and support your answer. Note: The light blue atoms are hydrogen atoms.

Short answer

(a) Illustration represents covalent hydrides.

(b) Illustration represents interstitial hydrides.

(c) Illustration represents ionic hydrides.

Step-by-step solution

Hydrides Definition

Hydrogen plus another element, whether a metal or a nonmetal, can combine to form hydrides. These hydrides can be categorised into three groups: ionic hydrides, covalent hydrides, and interstitial hydrides, depending on their structure and physical characteristics.

Covalent Hydrides

The illustration shown below is a representation of covalent hydrides.

In covalent hydrides, the hydrogen atom is covalently bonded to the atom of another element. Covalent hydrides are primarily compounds of hydrogen and nonmetals.

Examples of a covalent hydride include ${\text{H}}_2{\text{O,NH}}_3,C{H}_4$, etc.

Interstitial Hydrides

The illustration shown below is a representation of interstitial hydrides.

Interstitial hydrides are hydrides with transition metals in which the ratio of hydrogen atoms to metal atoms is not constant.

For example, the formula for titanium hydride can vary between$Ti{H}_{1,8}$ and $Ti{H}_2$.

Many of the interstitial hydrides have metallic properties such as electrical conductivity. Yet it is known that hydrogen is definitely bonded to the metal in these compounds, although the exact nature of the bonding is often not clear.

Ionic Hydrides

The illustration shown below is a representation of ionic hydrides.

Ionic hydrides are formed when molecular hydrogen combines directly with any alkali metal or with the alkaline earth metals $Ca,Sr$or Ba.

Therefore, illustrations of (a), (b), (c) represent covalent hydrides, interstitial hydrides, and ionic hydrides respectively.