The electron configuration of sulfur is 1s² 2s² 2p⁶ 3s² 3p⁴.
To determine the number of half-filled orbitals, we need to look at the last electron(s) added to the atom. In the case of sulfur, the last two electrons are added to the 3p subshell. The 3p subshell consists of three orbitals (3px, 3py, and 3pz), each capable of holding a maximum of two electrons.
Since sulfur has four electrons in the 3p subshell, it means that one of the orbitals will be half-filled with one electron. In other words, there is one half-filled orbital in an atom of sulfur.