The element that has the three half filled orbitals in 3P sublevel is
Phosphorus (P)
Phosphorus is in group 15 period 3 in the periodic table hence it is in atomic number 15. Phosphorus electronic configuration is 1S2 2S2 2P6 3S2 3P3 or [Ne] 3S2 3P3
From the electronic configuration of phosphorus the 3p3 sub level is unfilled since the p orbital can hold a maximum of 6 electrons.