Which of the following electron dot structures would have a charge of +2 and 1 valence electron?
a) Mg2+
b) B2+
c) Al2+
d) Na2+
You need to write the electron configuration for each neutral atom.
12Mg is 1s2 2s2 2p6 3s2
5B is 1s2 2s2 2p1
13Al is 1s2 2s2 2p6 3s2 3p1
11Na is 1s2 2s2 2p6 3s1
Taking 2 from Mg above leaves Mg2+ (1s2 2s2 2p6) with 6 outside. No.
Taking 2 from B above leaves B^2+ (1s2 2s1) with 1 outside. Yes.
Taking 2 from Al above leaves Al^2+ (1s2 2s2 2p6 3s1) with 1 outside. Yes
Taking 2 from Na above leaves Na^2+ (1s2 2s2 2p5) with 5 outside. No.