The total number of the elements above with 2 valence electron is _.

The total number of the elements above with 2 valence electron is four.

The electronic configurations of the elements are given:

He = 1s²

Be = 1s² 2s²

C = 1s² 2s² 2p²

Mg = 1s² 2s² 2p⁶ 3s²

Si = 1s² 2s² 2p⁶ 3s² 3p²

Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Valence electrons are those electrons which are present in outer most electronic shell.

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four elements

Explanation:

He = 1s²

Be = 1s² 2s²

C = 1s² 2s² 2p²

Mg = 1s² 2s² 2p⁶ 3s²

Si = 1s² 2s² 2p⁶ 3s² 3p²

Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Valence electrons are those electrons which are present in outer most electronic shell.

He, Be, Mg, Ca these four elements have 2 valence electrons.

While Si and C have four valance electrons.