Question

What numbers of electrons are found in a boron atom with an atomic number of 5 and a mass number of 11?

a) 5
b) 6
c) 11
d) 16

Answer 1

An atom of boron with an atomic number of 5 and a mass number of 11 contains five electrons. The electrons are distributed among the different subshells in the atom's energy levels.

Step-by-step explanation:

An atom of boron (atomic number 5) contains five electrons. The n = 1 shell is filled with two electrons and three electrons will occupy the n = 2 shell. Because any s subshell can contain only two electrons, the fifth electron must occupy the next energy level, which will be a 2p orbital. There are three degenerate 2p orbitals (m₁ = −1, 0, +1) and the electron can occupy any one of these p orbitals. When drawing orbital diagrams, we include empty boxes to depict any empty orbitals in the same subshell that we are filling.