What is the AXE (or AXmEn) classification for phosphine, PH3?

• A. AX3
• B. AX2E2
• C. AX2E
• D. AX3E

Answer: (D)

Verified step by step guidance

1. Identify the central atom and the surrounding atoms in the molecule PH\3. Here, phosphorus (P) is the central atom, and there are three hydrogen (H) atoms bonded to it.
2. Determine the number of bonding pairs (X) around the central atom. Since there are three hydrogen atoms bonded to phosphorus, the number of bonding pairs is 3, so X = 3.
3. Determine the number of lone pairs (E) on the central atom. Phosphorus in PH\3 has one lone pair of electrons, so E = 1.
4. Use the AXE notation where A represents the central atom, X represents the number of bonded atoms, and E represents the number of lone pairs on the central atom. For PH\3, this gives AX\3E.
5. Confirm that the AXE notation matches the molecular geometry and electron pair arrangement: three bonded atoms and one lone pair correspond to AX\3E.