An Atom with Three Electrons Has

Question

An atom with three electrons has:
A)one occupied orbital with three electrons.
B)two occupied orbitals, one of which has two electrons and the other has one.
C)three occupied orbitals, each of which contains one electron.
D)three energy shells, each of which contains one electron.

Accepted Answer

Each electron in an atom must occupy its own orbital before any orbital can have two electrons. Therefore, the three electrons in this atom must occupy two separate orbitals, one with two electrons and the other with one. Option A is not possible because if there is only one orbital with three electrons, at least two electrons would need to have the same spin, which is not allowed according to the Pauli exclusion principle. Option C is not possible because three electrons cannot occupy three separate orbitals in an atom with only three electrons. Option D is not accurate because the number of energy shells an atom has is determined by the number of its electrons, not the other way around.