Question

#1: Which element has the same number of energy levels as bromine (Br) and the same number of valence electrons as barium (Ba)?

A. potassium (K)

B,. beryllium (Be)

c. cadmium (Cd)

D. calcium (Ca)

***not too sure on this one... is it D. calcium (Ca) ??,

Answer 1

Bromine has 4 energy levels, because its electron number (35) fills four energy levels worth of orbitals. Barium's position on the periodic table gives it an unfilled orbital with 2 valence electrons. Calcium has 4 energy levels, and 2 valence electrons, so the answer is (D), Calcium.