Third Row Elements

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The third row elements are from sodium to argon. The build up of these eight elements proceeds exactly in the same manner as discussed above. Here 3s- and 3p-orbitals are filled in place of 2s- and 2p-orbitals as has been done in case of Li to Ne.

For e.g., the electronic configuration of sodium is:

Furthermore, for simplicity a common convention is used. In this, the detailed electronic configuration of the noble gas core preceding the valence shell is represented by the symbol of the noble gas in square bracket. Then, the configuration of the valence shell is written after the symbol.

For e.g., the electronic configuration of sodium may be written as:

Na (Z = 11): [Ne] 3s¹

The electronic configurations of the elements present in the third row of the periodic table are given below:

Na (Z =11) : [Ne]3s¹                     

Mg (Z =12) : [Ne]3s²

Al (Z = 13) : [Ne]3s²3p¹

Si (Z = 14) : [Ne]3s²3p²

P (Z = 15) : [Ne]3s²3p³

S (Z = 16) : [Ne]3s²3p⁴

Cl (Z = 17) : [Ne]3s²3p⁵

Ar (Z= 18) : [Ne]3s²3p⁶