Question

What is the electron configuration of a chlorine ion in a compound of BeCl2?

A. [2.8.7]-
B. [2.8.8]-
C. [2.8.8]+
D. 2.8.7

Answer 1

chlorine has 7 valence electrons in the outermost shell. when it forms an ionic bond with Be, it takes in 1 electron and achieves the noble gas configuration
since it has one more electron it gains a negative charge of -1.
anion is then - Cl⁻
electronic configuration of Cl atom is - [2,8,7]
after taking in the electron Cl⁻ - [2,8.8]⁻
answer is
B. [2.8.8]⁻

Answer 2

The electronic configuration of a chlorine ion in BeCl2 compound is

[2.8.8]^- (answer B)

chlorine atom gain on electron form Be to form chloride ions
chlorine atom has a electronic configuration of 2.8.7 and it gains one electron to form chloride ion with 2.8.8 electronic configuration