Question

Identify the isoelectronic elements

A. Cl-, F-, I-, Br-, At-

B. N3-, S2-, Br-, Cs+, Sr2+

C. P3-, S2-, Cl-, K+, Ca2+

D. Zn2+, Co2+, Cu2+, Cr2+, Cd2+

E. Ne, Ar, Kr, Xe, He

Answer 1

isoelectronic = same electron count

A. Cl-, F-, I-, Br-, At- = This is FALSE, since they are in the SAME family, meaning that the amount of electrons increase as the rows increases

B. N3-, S2-, Br-, Cs+, Sr2+ = This is a DIAGONAL, therefore, rows increases drastically the amount of electrons

C. P3-, S2-, Cl-, K+, Ca2+ = This is the correct answer

P = 15 electron, P-3 = 15+3 = 18 electrons

S = 16 electrons, S-2 = 16+2 = 18 electrons

Cl = 17 electrons, Cl- = 17+1 = 18 electrons

K+ = 19 electrons, K+ = 19-1= 18 electrons

Ca = 20 electrons, Ca+2 = 20-2 = 18 electrons

D. Zn2+, Co2+, Cu2+, Cr2+, Cd2+ = They are all +2 charged, so it is impossible to have the same electron count in the SAME family

E. Ne, Ar, Kr, Xe, He = Similar as in A, these are a single FAMILY, noble gases have all different electorn count