Question

What is hydride? How many types of hydrides are there? Explain example.

Answer 1

Hint : The term hydride refers to an anion of hydrogen. Hydrogen generally forms a proton, but when it forms a compound with an element with lower electronegativity, it forms a hydride.

Complete Step By Step Answer:
Let us start this question by understanding the term hydride. ‘Hydride’ is formally the anion of hydrogen, i.e. when hydrogen makes a compound with an element of lesser electronegativity. It is represented as ${{H}^{+}}$ As we can see, in hydrides, the oxidation number of hydrogen is $-1.$
When hydrogen combines with different elements it forms different type of hydride;
Ionic hydride: When hydrogen forms a compound with group IA elements, it forms an ionic hydride. Example: Lithium Hydride, Sodium Hydride, Potassium hydride.
Molecular hydride: These kinds of hydrides are formed by electron-rich compounds (generally p-block elements). Example: Water and ammonia.
Interstitial hydride: These are also known as metallic halides. This type of halide is generally formed by d-block elements. Example: Zinc Hydride and Scandium Hydride.
Electron precise hydride: The compounds which have the exact number of electrons to form normal covalent bonds form electron precise halides. Group 14 compounds form this type of element. Example: Methane.
Electronegativity of hydrogen is $2.2.$ Fluorine is the most electronegative element of the periodic table, with electronegativity about $3.98.$

Note :
In group $6,$ Chromium is the only element to form a hydride. Elements from Group $7,\text{ }8$ and $9$ of the periodic table do not form hydride. This is also known as hydride gap. Hydride gap occurs because the electronegativity of these elements is higher than that of hydrogen.