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Alastair Croxton

Is AlF3 a Lewis acid?

Brenda Tucker  Follow

You may want to find out more about complex ions and ligands.

To be a Lewis acid, the ion/atom (ion in this case) needs to be able to accept electron pairs from another species. This means that it needs to have empty orbitals. Usually elements and ions from Period 3 have empty/partially-filled d orbitals. I don't have a Periodic Table with me, so I can't provide a definite answer.

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Andrew Curl  Follow

AlCl3 is electron deficient. It has three electrons in its valence shell. So when it forms a covalent compound with chlorine it forms three single bonds with chlorine. It doesn't form an octet by doing so thus it can take two more electrons by forming a coordinate bond to become an octet and thus it behaves as Lewis acid. (Lewis acid is defined as compound which can take electron from a donor compound)

Hope it helps.

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Asad Hussain  Follow

Lewis acid is therefore any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor. All cations are Lewis acids since they are able to accept electrons. Examples include copper (Cu2), iron (Fe2+ and Fe3+), and hydrogen ion (H+). An atom, ion, or molecule with an incomplete octet of electrons can accept electrons. Examples include boron trifluoride (BF3) and aluminum fluoride (AlF3)

HOPE THIS WILL HELP YOU

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Digiworldofagriculture  Follow

yes

An atom, ion, or molecule with an incomplete octet of electrons can act as an Lewis acid.

eg.-BF3,ALF3

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Aphotic Sapian  Follow

AlCl3 can dimerise to form Al2Cl6 so it does not have vacant p orbital to accept lone pair.

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Brodie Brickey  Follow

It is not. However, the magnesium ion, Mg2+ is a Lewis acid. You don't have to search far to find examples. Well, dissolve the said chloride in water and Mg2+ will form a coordination complex with water: [Mg(OH2)6]2+. It's a classic examples of Lewis acid (magnesium) reaction with Lewis base (water).

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Dawood Khan  Follow

In AlF3, Al atom is bonded to 3 F atoms by sharing 3 bonding pairs of electrons. In other words, the valence shell of Al is occupied by 6 electrons. Therfore Al does not fulfill the octet rule and AlF3 is electron deficient. Electron deficient molecules are Lewis acid.

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Ayesha Qurat ul Ain  Follow

Any species having a vacant orbital is electron deficient as it has tendency to accommodate electronic pair and thus it can act as lewis acid. Furthermore, three fluorines (4.0) being more electronegative than Aluminium makes it highly electron deficient molecule. It increases its acidic tendency further. When a lewis base like ammonia approches it, AlF3 accepts a lone pair from it forming a lewis adduct. (Acid base reaction)

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Allan Nicholas  Follow

AlF3 is an ionic compound.

Those species which have the central atom with less than eight electron in the outermost shell or valence shell are considered as hypovalent species.

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B J Quinn  Follow

If you draw the Lewis structure for the molecule, you see three single bonds joining the Al to each of the three chlorine atoms. Those three bonds will be sp2 hybrids, made of an admixture of an s and two p orbitals, which means there is an unused p orbital that is empty (no lone pairs). that unused p orbital can accept a pair of electrons from some other molecule or part of a molecule that has a lone pair to satisfy its octet. So, AlCl3 can act as a Lewis acid.

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