A very simple and stupid question on shapes of molecules and the VSEPR theory

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Leah.J
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As far as I understand, the VSEPR theory is used to find the shapes of molecules ... Molecules are covalently bonded

How then, can I use the VSEPR theory to determine the shape of BF3 ?
Boron is a metal, Flourine is a non metal so the bond between them should be an ionic compound and this should be a compound not a molecule , so what am I missing out here ?
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Ðeggs
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I’m no chemistry expert, but considering the values of the first ionisation energy, especially as boron is a very small molecule, would mean that the energy required to form a B3+ ion is far too great to occur in standard reaction conditions. Therefore boron does not form ions, and instead forms three covalent bonds as it has three valencd electrons, which require much less energy to create and are more energetically favourable. Boron is an odd one out!
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charco
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(Original post by Leah.J)
As far as I understand, the VSEPR theory is used to find the shapes of molecules ... Molecules are covalently bonded

How then, can I use the VSEPR theory to determine the shape of BF3 ?
Boron is a metal, Flourine is a non metal so the bond between them should be an ionic compound and this should be a compound not a molecule , so what am I missing out here ?
1. Boron is not a metal
2. Element no. 9 is spelled F L U O R I N E
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Pigster
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(Original post by Deggs_14)
I’m no chemistry expert, but considering the values of the first ionisation energy, especially as boron is a very small molecule, would mean that the energy required to form a B3+ ion is far too great to occur in standard reaction conditions. Therefore boron does not form ions, and instead forms three covalent bonds as it has three valencd electrons, which require much less energy to create and are more energetically favourable. Boron is an odd one out!
For someone who isn't a chemistry expert you sure sound like one.
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Leah.J
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(Original post by charco)
1. Boron is not a metal
2. Element no. 9 is spelled F L U O R I N E
What about B E R Y L L I U M chloride ? We can use the VSEPR theory to determine its shape even though it should be a compound
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charco
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(Original post by Leah.J)
What about B E R Y L L I U M chloride ? We can use the VSEPR theory to determine its shape even though it should be a compound
It should be a compound and it is a compound.

It is, however, a simple covalent compound (in the gaseous state). In the solid state it has a giant covalent lattice.

Beryllium is too small an atom to form a stable 2+ ion in the presence of chloride ions. Be2+ would be far too polarising due to the high charge density to allow the formation of an ionic chloride.
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Leah.J
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(Original post by charco)
It should be a compound and it is a compound.

It is, however, a simple covalent compound (in the gaseous state). In the solid state it has a giant covalent lattice.

Beryllium is too small an atom to form a stable 2+ ion in the presence of chloride ions. Be2+ would be far too polarising due to the high charge density to allow the formation of an ionic chloride.
I have a question on complex ions and ligands too, if you don't mind.
When do they form ? Or are the transition metal ions always complexes ? For example, Is Fe(NO3)3 (aq) really Fe(H20)6(NO3)3 ?

Also, I understood from my teacher's notes that hexaaqua ions are proton donors, and that in water, the ion would continue to donate protons until it forms a ppt. But that confused me, because doesn't that mean no complex ion would remain an ion in solution ? And that transition metal ions wouldn't be able to form compounds ? Dumb questions, maybe, but I'm confused.
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username4550332
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(Original post by charco)
It should be a compound and it is a compound.

It is, however, a simple covalent compound (in the gaseous state). In the solid state it has a giant covalent lattice.

Beryllium is too small an atom to form a stable 2+ ion in the presence of chloride ions. Be2+ would be far too polarising due to the high charge density to allow the formation of an ionic chloride.
:ta: for the explanation!
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charco
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(Original post by Leah.J)
I have a question on complex ions and ligands too, if you don't mind.
When do they form ? Or are the transition metal ions always complexes ? For example, Is Fe(NO3)3 (aq) really Fe(H20)6(NO3)3 ?

Also, I understood from my teacher's notes that hexaaqua ions are proton donors, and that in water, the ion would continue to donate protons until it forms a ppt. But that confused me, because doesn't that mean no complex ion would remain an ion in solution ? And that transition metal ions wouldn't be able to form compounds ? Dumb questions, maybe, but I'm confused.
In aqueous solution they are always complexes, the hexaaqua complex. The nitrate ions are balancing ions and not part of the complex.

The hexaaqua complex is a proton doner when the complex ion metal charge is high.They can be made to donate protons by adding a base in which case there is precipitation of the hydroxy complex.
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