Question

which is the ground state electronic configuration of an alkaline earth metal?

a) ( 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 6 } 4 s ^ { 2 } 3 d ^ { 10 } 4 p ^ { 2 } )
b) ( 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 6 } 4 s ^ { 2 } )
c) ( 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 6 } 4 s ^ { 2 } 3 d ^ { 2 } )
d) ( 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 6 } 4 s ^ { 1 } )

Explanation:

Alkaline earth metals are in Group 2 of the periodic table. Their general valence - shell electron configuration is \(ns^{2}\).

• Option A: The electron configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{2}\) corresponds to a non - alkaline earth metal (germanium, for example).
• Option B: The electron configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}\) has the outer - shell configuration \(4s^{2}\), which is characteristic of an alkaline earth metal (calcium).
• Option C: The electron configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{2}\) corresponds to a transition metal (titanium).
• Option D: The electron configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\) corresponds to an alkali metal (potassium).

Answer:

B. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}\)