The Student Room Group

Phosphorus hexafluoride ion: Lewis Dot and Cross diagram

I need to draw a Lewis dot and cross diagram for the phosphorus hexafluoride ion for my IB Chemistry HL. I tried but ended up with the phosphorus atom having 12 shared electrons with 6 fluorine atoms. But doesn't phosphorus only have 5 electrons to covalently bond with? Ahhhh. :s-smilie:

Help would be much appreciated :smile:

Merry [Belated] Christmas ! :biggrin:
Original post by fablesofgray
I need to draw a Lewis dot and cross diagram for the phosphorus hexafluoride ion for my IB Chemistry HL. I tried but ended up with the phosphorus atom having 12 shared electrons with 6 fluorine atoms. But doesn't phosphorus only have 5 electrons to covalently bond with? Ahhhh. :s-smilie:

Help would be much appreciated :smile:

Merry [Belated] Christmas ! :biggrin:


Just do it one step at a time...

Phosphorus has 5 outer electrons = 5
Each fluorine provides 1 electron = 6
The negative charge must be added in = 1
-------------------------------------------------------- add together
Total electrons around the phosphorus = 12

This makes 6 pairs = electronically octahedral

Each P-F bond requires 2 electrons and there are 6 P-F bonds = 12 electrons

Hence all electrons used up in bonding. Ionic shape is also octahedral.
Reply 2
Original post by charco
Just do it one step at a time...

Phosphorus has 5 outer electrons = 5
Each fluorine provides 1 electron = 6
The negative charge must be added in = 1
-------------------------------------------------------- add together
Total electrons around the phosphorus = 12

This makes 6 pairs = electronically octahedral

Each P-F bond requires 2 electrons and there are 6 P-F bonds = 12 electrons

Hence all electrons used up in bonding. Ionic shape is also octahedral.


Thank you! :smile:

Haven't learnt about VSEPRT and hybridisation yet... but will do so soon :smile:

Quick Reply

Latest