Question

Explain why a magnesium atom is smaller than atoms of both sodium and calcium

Answer 1

The Mg atom is smaller than Na as it has 1 more proton, which increases its effective nuclear charge. The nucleus exerts a greater force of attraction that brings the electrons closer inward, and so the atom is smaller.
Mg is smaller than Ca because Ca has an extra electron shell. Also, the electrons in lower shells of Ca shields the valence electrons from the nuclear charge and so the atom can be bigger.

Answer 2

oh ok thanks that makes snese

Answer 3

No problem =)

Answer 4

great answer