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Between FeCl3 and AlCl3, which is more covalent?
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Oleksandr Zginnyk
Between FeCl3 and AlCl3, which is more covalent?
In basic chemistry, it would be expected that both FeCl3 and AlCl3 would be pure ionic compounds.
This is where chemistry starts to get interesting because they are NOT pure ionic compounds.
Chloride ions can be thought of (only for imagining purposes) to be spheres of negatively charged “mist”. The mist being the electron clouds around the central nucleus. Because they have one electron “too many”, they are very wibbly-wobbly and easily distorted with less than one nuclear + charge per electron.
The metals each lose 3 electrons, so they remaining electrons are drawn closer to the nucleus, since each electron now has a greater “share” of attraction from the nuclear charge with more than one nuclear + charge per electron.
Al^(3+) is much, much smaller than a Fe(3+) ion because it has fewer shells. This property is quantified by the “charge to radius ratio” → e/r ← the higher the value, the greater the ability to distort or ”polarise” the electron “mist” or cloud.
Now - think to electrostatics demonstrations with Van der Graaf generators, and what you know about lightning conductors…
Electrical charge is dissipated faster from a sharp point.
This is why you approach a charged sphere with an earthed needle point between you and the sphere and also why lightning strikes the lightning conductor rather than the tower.
Al^(3+) is a sharper point in space than Fe^(3+) so the Al^(3+) affects the electric field of the chloride ions much more.
BOTH distort the wibbly wobbly negative “mist” around the Cl^(-) ion, but the Al(3+) does it most.
When the distortion occurs, the “mist” of electrons wraps around the positive ion - or you could say that the metal ion “sinks inside” the electron “mist”.
When this “overlap” happens we have, to some extent, a covalent bond.
The “degree of covalency” for AlCl3 is greater than for FeCl3 for the reasons just stated above.
I hope this helps.
Try to visualise what is going on - it helps understanding and understanding is knowledge and knowledge is power!
Understanding saves a great deal of effort compared to trying to remember unrelated facts.
In basic chemistry, it would be expected that both FeCl3 and AlCl3 would be pure ionic compounds.
This is where chemistry starts to get interesting because they are NOT pure ionic compounds.
Chloride ions can be thought of (only for imagining purposes) to be spheres of negatively charged “mist”. The mist being the electron clouds around the central nucleus. Because they have one electron “too many”, they are very wibbly-wobbly and easily distorted with less than one nuclear + charge per electron.
The metals each lose 3 electrons, so they remaining electrons are drawn closer to the nucleus, since each electron now has a greater “share” of attraction from the nuclear charge with more than one nuclear + charge per electron.
Al^(3+) is much, much smaller than a Fe(3+) ion because it has fewer shells. This property is quantified by the “charge to radius ratio” → e/r ← the higher the value, the greater the ability to distort or ”polarise” the electron “mist” or cloud.
Now - think to electrostatics demonstrations with Van der Graaf generators, and what you know about lightning conductors…
Electrical charge is dissipated faster from a sharp point.
This is why you approach a charged sphere with an earthed needle point between you and the sphere and also why lightning strikes the lightning conductor rather than the tower.
Al^(3+) is a sharper point in space than Fe^(3+) so the Al^(3+) affects the electric field of the chloride ions much more.
BOTH distort the wibbly wobbly negative “mist” around the Cl^(-) ion, but the Al(3+) does it most.
When the distortion occurs, the “mist” of electrons wraps around the positive ion - or you could say that the metal ion “sinks inside” the electron “mist”.
When this “overlap” happens we have, to some extent, a covalent bond.
The “degree of covalency” for AlCl3 is greater than for FeCl3 for the reasons just stated above.
I hope this helps.
Try to visualise what is going on - it helps understanding and understanding is knowledge and knowledge is power!
Understanding saves a great deal of effort compared to trying to remember unrelated facts.
In basic chemistry, it would be expected that both FeCl3 and AlCl3 would be pure ionic compounds.
This is where chemistry starts to get interesting because they are NOT pure ionic compounds.
Chloride ions can be thought of (only for imagining purposes) to be spheres of negatively charged “mist”. The mist being the electron clouds around the central nucleus. Because they have one electron “too many”, they are very wibbly-wobbly and easily distorted with less than one nuclear + charge per electron.
The metals each lose 3 electrons, so they remaining electrons are drawn closer to the nucleus, since each electron now has a greater “share” of attraction from the nuclear charge with more than one nuclear + charge per electron.
Al^(3+) is much, much smaller than a Fe(3+) ion because it has fewer shells. This property is quantified by the “charge to radius ratio” → e/r ← the higher the value, the greater the ability to distort or ”polarise” the electron “mist” or cloud.
Now - think to electrostatics demonstrations with Van der Graaf generators, and what you know about lightning conductors…
I hope this helps.
Try to visualise what is going on - it helps understanding and understanding is knowledge and knowledge is power!
Understanding saves a great deal of effort compared to trying to remember unrelated facts.
In basic chemistry, it would be expected that both FeCl3 and AlCl3 would be pure ionic compounds.
This is where chemistry starts to get interesting because they are NOT pure ionic compounds.
Chloride ions can be thought of (only for imagining purposes) to be spheres of negatively charged “mist”. The mist being the electron clouds around the central nucleus. Because they have one electron “too many”, they are very wibbly-wobbly and easily distorted with less than one nuclear + charge per electron.
The metals each lose 3 electrons, so they remaining electrons are drawn closer to the nucleus, since each electron now has a greater “share” of attraction from the nuclear charge with more than one nuclear + charge per electron.
Al^(3+) is much, much smaller than a Fe(3+) ion because it has fewer shells. This property is quantified by the “charge to radius ratio” → e/r ← the higher the value, the greater the ability to distort or ”polarise” the electron “mist” or cloud.
Now - think to electrostatics demonstrations with Van der Graaf generators, and what you know about lightning conductors…
I hope this helps.
Try to visualise what is going on - it helps understanding and understanding is knowledge and knowledge is power!
Understanding saves a great deal of effort compared to trying to remember unrelated facts.
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