Question

What are the s-block elements?

Answer 1

Group I A and IIA the alkaline metals and alkaline earth metals.

Explanation:

Group IA metals such as sodium, potassium, are elements that have valance electrons in the s orbitals.

Group II A metals such as magnesium, calcium are elements that have valance electrons in the s orbitals.

Answer 2

These are the alkali metals, and the alkaline earths.

Explanation:

And look at your Periodic Table; the leftmost COLUMN, `Li, Na,`
`K, Rb, Cs, Fr` are the alkali metals; i.e. this is Group 1 of the Periodic Table, whose members have a single VALENCE electron, i.e. `"s-electrons"`.

And the second-most column, Group 2, the so-called alkaline earths, `Be, Mg, Ca, Sr, Ba, Ra`, have a complete `"s-valence"` shell. And thus both the Group 1 and Group 2 elements constitute the `"s-block"`.

Hydrogen, `Z=1`, is a bit of a special case. Its metallic properties are only manifested under special circumstances, and many Periodic Tables offset hydrogen from the alkali metals.