# How many unpaired electrons are in a boron atom?

The configuration of boron is $1 {s}^{2} 2 {s}^{2}$$2 {p}^{1}$ which means only the $p$ electron is unpaired.
However, when bonding in a compound, one of the $2 s$ electrons is promoted into the $2 p$ subshell, with the result that $s {p}^{2}$ hybrid orbitals are created, and three bonding orbitals exist.