How many unpaired electrons are in a boron atom?

1 Answer
Feb 21, 2017

Answer:

In the ground state, only one. But for bonding, all three valence electrons are used, and the atom acquires a slightly excited state.

Explanation:

The configuration of boron is #1s^2 2s^2##2p^1# which means only the #p# electron is unpaired.

However, when bonding in a compound, one of the #2s# electrons is promoted into the #2p# subshell, with the result that #sp^2# hybrid orbitals are created, and three bonding orbitals exist.