The 13 elements of the IA and IIA Group located in the leftmost and two vertical columns in the amplified periodic table are called elements of S-block.

In other words, Hydrogen, alkali metals, Alkaline earth metals are called S-Block elements.

The last electron in the elements of this block enters s-subshell.

General Characteristics of s-Block elements

Electronic Configuration

The last electron of this block’s elements enters in s-subshell.

All subshells before this are fully loaded! S-subshell can have 1 or 2 electrons.

So the Electronic configuration is ns1-2 for s-block elements.

Valency

The number of electrons in the Outermost shell of s-block elements is the valence of that element. The valence of these elements is fixed.

So the valence of H, Li, Na, K, Rb, Cs, and Fr is 1 and Be, Mg, Ca, Sr, Ba and Ra elements valence is 2.