Question

Why s- block element known as alkali metals?

Answer 1

Hint : s- block elements are the first two groups of the periodic table i.e. s – block elements comprising the group $- 1$ and the group $2$ of the periodic table. Group $1$ is known as the alkali metals and group 2 is known as the alkaline earth metal.

Complete Step By Step Answer:
Group 1 of the periodic table i.e. alkali metals are the groups of the soft metal elements having very low electronegativity values.
: Group 1 of the periodic table contains elements from top to bottom as follows:
Hydrogen $(H)$ , Lithium $(Li)$ , sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), Francium (Fr).
Now as we have basic information about the alkali metals, let's understand the reason behind their naming.
Group 1 of the s-block element is known as the alkali metals due to its reaction with water.
So, Group 1 of the s-block element reacts with water to form ‘alkalies’ i.e. strong bases capable of neutralising strong acids.
Alkalies are basically the hydroxide compound of these elements (alkali elements).
Let’s have a look at the few examples:
Sodium reacts with water to form sodium hydroxide, potassium combines with water to form potassium hydroxide, and similarly we have Lithium hydroxide.
These reactions are exothermic in nature.
The oxides of the alkali metals are highly soluble in water.

Note :
Alkali metal hydrides can be seen as white crystalline solid with a hygroscopic nature. These hydroxides of alkali metals are highly soluble in water, releasing a large amount of heat i.e. an exothermic process. This solubility decreases down the group as the size of the metals keep on increasing down the group.