The Student Room Group
Reply 1
2. SF2 can react with F2 as S(+2) can be oxidised by F2 to be S(+4) {the energy of forming bonds S-F can compensate the energy needed to ionise S from 2nd state to 4th state)
But MgF2 cannot as the energy of forming bonds is not enough to break bonds, and 4th ionsation energy of Mg is very great).
The 3 electrons of Al are covalently bonded with Florine to AlF3. However, the thing which is to be noticed that AlF3 has an empty orbital which can accomodate 2 more electrons. From the second AlF3 the Florine donates 2 pair of electrons to the empty orbital of first AlF3 and this done by the first one too, forming two dative covalent bonds. thus, forming ALF6.
Reply 3
driving_seat
The 3 electrons of Al are covalently bonded with Florine to AlF3. However, the thing which is to be noticed that AlF3 has an empty orbital which can accomodate 2 more electrons. From the second AlF3 the Florine donates 2 pair of electrons to the empty orbital of first AlF3 and this done by the first one too, forming two dative covalent bonds. thus, forming ALF6.

Well, I think you mixed up Al2F6 and (AlF6)3-
I think Al here receives pairs of electrons from anions F-, not from F in other AlF3.
If F- is attached to AlF3 then how it will form Al2F3. It is surely a dative covalent. better if u consult any book to be clear.
Cryolite is Na3AlF6

This clearly is an octahedral ion with the aluminium being at the centre of the octahedron. The overall charge on the ion is 3- as shown by the Na3, this means that the aluminium 3+ is counterbalanced by six fluoride ions to make the overall three minus.

The fluoride ion's electron pairs are coordinated into the aluminium's hybridised orbitals sp3 d2.

Aluminium can do this as it belongs to the 3rd period of the periodic table where the 3d orbitals are available for bonding of this kind.
Reply 6
charco
Cryolite is Na3AlF6

This clearly is an octahedral ion with the aluminium being at the centre of the octahedron. The overall charge on the ion is 3- as shown by the Na3, this means that the aluminium 3+ is counterbalanced by six fluoride ions to make the overall three minus.

The fluoride ion's electron pairs are coordinated into the aluminium's hybridised orbitals sp3 d2.

Aluminium can do this as it belongs to the 3rd period of the periodic table where the 3d orbitals are available for bonding of this kind.


I'd take this guys answer if I were you. :p: