Question

The metal that forms nitride by reacting directly with ${N_{_2}}$ air:
A.$K$
B.$Cs$
C.$Li$
D.$Rb$

Answer 1

To answer this question, you should recall the concept of properties of periodic table elements. The elements which are highly reactive in nature can react directly with nitrogen in the air.

Complete step by step answer:
Lithium shows similarities with magnesium in its chemical behaviour because they have similar size and charge/size ratio. They have similar electronegativity. This type of diagonal similarity is commonly referred to as the diagonal relationship in the periodic table. Among Alkali metals lithium is the diagonal neighbour of Magnesium and reacts with air forming both oxide and nitride.
The reactions of can be shown by:
$6Li + N_2 \to 2L{i_3}N$ and $4Li + {O_2} \to 2L{i_2}O$

Hence, the correct option is option C.

Additional information:
The properties shared are:
(i) Both $Li{\text{ }}$ and $Mg$ react slowly with cold water.
(ii) The oxides of both $Li$ and $Mg$ are much less soluble in water and their hydroxides decompose at high temperature.
(iii) Both $Li$ and $Mg$ form nitrides by reacting with nitrogen gas in air.
(iv) Neither $Li$ nor $Mg$ form peroxides or superoxides.
(v) The carbonates of both $Li$ and $Mg$ are covalent. Also, these decompose on heating.
(vi) $Li$ and $Mg$ do not form solid bicarbonates.
(vii) Chlorides of both $Li$ and $Mg$ are soluble in ethanol owing to their covalent nature. These salts are deliquescent. They crystallize from aqueous solutions as hydrates.

Note:
Uses of Lithium:
Bromine and lithium chloride together form concentrated brine which absorbs the humidity under high temperature. Brine is used in the manufacturing of air conditioning systems.
Alloys of the metal with manganese, cadmium, copper, and aluminium are used to make aircraft’s parts.
The carbonate is used in medicine as an antidepressant and pottery industry.