Question

2. Why would a calcium (Ca) atom be larger than a bromine (Br) atom even

though they both have 4 energy levels? *

Answer 1

Within a period, the atom size decreases with increasing group number (from left to right), since the nuclear charge and the number of external electrons increase within the period, but the number of shells does not. The electrons are more strongly attracted to the nucleus and are therefore closer to the nucleus.