Answer:
The electron configuration of a chlorine ion in a compound of BeCl2 is
1s²2s²2p⁶3s²3p⁶
Step-by-step explanation:
Beryllium chloride (BeCl2) is an ionic compound where Be is an alkaline earth metal (group 2) and Cl is a halogen atom (group 17).
Alkaline earth metals have a charge of +2 while halogens exhibit a -1 charge. Hence in BeCl2 each Be atom exists as Be2+ cation and Cl exists as Cl- anion.
The atomic number of Cl = 17. The valence electron configuration for the neutral atom is:
Cl(Z=17) = 1s²2s²2p⁶3s²3p⁵
The chloride ion has an addition electron, therefore
Cl⁻(Z = 17+1 = 18) = 1s²2s²2p⁶3s²3p⁶