Question

Explain what is wrong with each molecular geometry and provide the correct molecular geometry, given the numbers of lone pairs and bonding groups on the central atom. Match the words in the left column to the appropriate blanks in the sentences on the right. ResetHelp In structure (a), four pairs of electrons give electron geometry. The lone pair would cause lone pair-bonded pair repulsions and would have molecular geometry. In structure (b), five pairs of electrons give electron geometry. The lone pair occupies an equatorial position to minimize lone pair-bonded pair repulsions, and the molecule would have molecular geometry. In structure (c), six pairs of electrons give electron geometry. The two lone pairs would occupy opposite positions to minimize lone pair-lone pair repulsions, and the molecule would have molecular geometry.

Answer 1

Answer:

Four electron pairs give a tetrahedral geometry. Four electron pairs with one lone pair gives a trigonal pyramidal molecular geometry.

Five electron pairs give a trigonal bipyramidal geometry. Five electron pairs with one lone pair gives a seesaw molecular geometry.

Six electron pairs give octahedral geometry. Six electron pairs with two lone pairs give a square planar geometry.

Explanation:

According to the valence shell electron pair repulsion theory (VSEPR), the molecular shape of any compound depends on the number of electron pairs present in the valence shell of it's central atom; both bonding and non bonding pairs of electrons.

The repulsion between two bonding pairs of electrons on the valence shell is very little compared with the repulsion between a bonding pair and a non bonding pair. The greatest repulsion of electron pairs is found between two non bonding pairs of electrons on the valence shell.

This repulsion that characterizes the presence of non bonding pairs of electrons on the valence shell of the central atom in a molecule usually lead to a distortion of the molecular shape predicted on the basis of the number of electron pairs present. This accounts for the deviation of molecular geometries from each of the expected electron pair geometries in the answer above.