Final answer:
The compound PBr3 requires 12 electrons.
Step-by-step explanation:
The compound PBr3 is made up of one phosphorus atom (P) and three bromine atoms (Br). To determine the number of electrons needed for this compound, we need to know the electron configuration of each element. Phosphorus has an electron configuration of 1s² 2s² 2p⁶ 3s² 3p³, meaning it has 5 valence electrons. Bromine has an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵, meaning it has 7 valence electrons.
In the compound PBr3, the P atom will use its 3d and 4s electrons to bond with the Br atoms. Each Bromine atom will share one electron with the Phosphorus atom, resulting in the formation of three covalent bonds. Therefore, the number of electrons needed for the compound PBr3 is 5 (from phosphorus) + 7 (from bromine) = 12 electrons.