Question

how many unpaired electrons are in a p (phosphorus) dot structure: 4 1 5 3 2

Explanation:

Step1: Determine phosphorus's electron configuration

Phosphorus (P) has atomic number 15. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$.

Step2: Analyze the outer - shell electrons

The outer - shell is the 3rd shell with $3s^{2}3p^{3}$ electrons. The 3s sub - shell is full with 2 paired electrons. The 3p sub - shell has 3 orbitals. According to Hund's rule, electrons will occupy separate orbitals with parallel spins before pairing up. So, the 3 electrons in the 3p sub - shell are unpaired.

Answer:

D. 3