How many valence electrons are in boron?

Boron has three valence electrons. It is in group 13. 1st energy level ------- 2 e- 2nd energy level-------8 e- 3rd energy level ------3 e-

Outermost energy level is the the 3rd energy level and it has three electrons. Valence electrons are the electrons in the last energy level of an atom. You can also just look at the group number (13) and the second number is the number of valence electrons. This works for all elements in the periodic tale except for the transition metals.