How do we determine number of unpaired electrons?

[Veronica Soliman 4H]

Referring to chapter 2 in 6th edition #'s 2.53 and 2.51

Asking to find unpaired e- in Bi, Si, Ta, and Ni
Also how many unpaired e- in Ga, Ge, As, Se, and Br? How do you solve these?

[Vy Lu 2B]

You should write out the electron configurations of those ions and elements, and from there, you would identify what subshell is not filled completely; apply Pauli exclusion rule and Hund's rule to determine how many unpaired electrons are present in the ions and elements.