Question

answer the questions in the table below about the shape of the phosphorus tribromide (pbr₃) molecule. how many electron groups are around the central phosphorus atom? note: one \electron group\ means one lone pair, one single bond, one double bond, or one triple bond. what phrase best describes the arrangement of these electron groups around the central phosphorus atom? (you may need to use the scrollbar to see all the choices.)

Explanation:

Step1: Determine valence - electrons of P

Phosphorus (P) is in Group 5A, so it has 5 valence electrons. Bromine (Br) is in Group 7A and has 7 valence electrons. In $PBr_3$, P is the central atom. P forms 3 single bonds with 3 Br atoms.

Step2: Calculate electron - groups

Each P - Br single bond is an electron - group, and there is 1 lone pair on P. So the number of electron - groups around the central P atom is 4 (3 bonding pairs + 1 lone pair).

Step3: Determine electron - group arrangement

According to VSEPR (Valence - Shell Electron - Pair Repulsion) theory, when there are 4 electron - groups around a central atom, the electron - group arrangement is tetrahedral.

Answer:

How many electron groups are around the central phosphorus atom? 4
What phrase best describes the arrangement of these electron groups around the central phosphorus atom? Tetrahedral