Question

What are hydrides? What are the main 3 types of hydrides?

Answer 1

Hydrides:-

The binary compounds of hydrogen with different elements are called hydrides.

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1. Ironic/ Saline Hydrides:-

• Compounds of Hydrogen with s- block elements except Be and Mg are called ionic hydrides. Ex:- LiH.

• These hydrides are non-conducting and non- volatile in solid state.

• On electrolysis of this type of hydrides, hydrogen is liberated at anode.

• On reaction with water they form hydrogen:-

$NaH + {H}_{2}O \rightarrow NaOH+ {H}_{2}$

• These hydrides can form complex hydrides which are good in conducting.

$4LiH + Al{Cl}_{3} \rightarrow 3LiCl+ LiAl{H}_{4}$

$LiAl{H}_{4}$ = Lithium aluminium hydride.

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2. Metallic hydrides:-

• The compounds of hydrogen with d and f block elements are called Metallic hydrides. Ex:- $Zr{H}_{x}$

• Properties of the hydrides are similar to their parents metals.

• In this type of hydrides hydrogen occupies the interstitial sites of metallic lattice.

• This type of hydrides have variavle composition.

• The compounds are conducting and non-brittle.

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3. Covalent Hydrides :-

• The compounds of hydrogen with p- block elements are called covalent hydrides. Ex:- HF.

• These hydrides exist as molecules.

• They don't conduct electricity.

• They are devided into 3 categories:-

1. Electron deficient hydrides :- Have less than 8 electrons in its outermost shell.

2. Electron precise hydrides :- Have 8 electrons in its outermost shell.

3. Electron rich hydrides :- Have more than 8 electrons in its outermost shell.