Question

what is the group number of this atom? what is the period number of this atom?

Explanation:

Step1: Determine number of valence electrons

The number of protons (P = 33) gives the atomic number. The electron - shell configuration of an atom with atomic number 33 is 2, 8, 18, 5. The outermost shell has 5 electrons.

Step2: Relate valence electrons to group number

For main - group elements, the group number is equal to the number of valence electrons plus 10 (for groups 13 - 18) or is equal to the number of valence electrons (for groups 1 - 2 and 13 - 18). Since the atom has 5 valence electrons, it is in group 15.

Answer:

15