What is the ionic bond formation of aluminum and chlorine?

1 Answer
Ernest Z.
Feb 2, 2014

Aluminum and chlorine form covalent bonds, not ionic bonds.

Explanation:

The #"Al-Cl"# bond is polar covalent.

This is consistent with the fact that aluminum chloride changes directly from a solid to a gas at the relatively low temperature of 180 °C.

Al has three valence electrons.

outpost1.stellimare.com

#"Cl"# has seven valence electrons.

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#"Al"# and #"Cl"# must achieve their octets by sharing electrons.

chemwiki.ucdavis.edu

#"AlCl"_3# is still electron deficient. The #"Al"# has only six electrons in its valence shell.

Measurements show that the formula of the vapour is #"Al"_2"Cl"_6#.

It exists as a dimer (two molecules joined together) in which two electrons from one #"Cl"# are shared with the #"Al"# of the other #"AlCl"_3# molecule to form a coordinate bond. In this way. all atoms gain an octet.

chemwiki.ucdavis.edu

Energy is released when the two coordinate bonds are formed, so the dimer is more stable than two separate #"AlCl"_3# molecules.

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