Question

If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom, the structure Y---X---Y (2 lone pairs around X) could be abbreviated as XY2Z2. Classify these structures according to their shape.

Molecular Geometries:         

linear

bent 120

bent 109

trigonal pyramidal

T-shaped

see saw

square planar

square pyramidal

Possiblities:

XY4Z2

XY5Z

XY2Z

XY2Z3

XY4Z

XY2Z2

XY3Z2

XY3Z

Answer 1

Concepts and reason

Valence shell electron pair repulsion model predicts the shapes of molecules and ions based on the number of bond pairs and lone pairs present on the central atom of a molecule.

Fundamentals

The main postulates of VSEPR model is as follows:

(i) The shape of molecule depends on the electron-electron repulsions present in the valence shell of the central atom.

(ii) The repulsive interactions between the electron pairs are in the following order:

(iii) If the central atom forms multiple bonds, then the order of electron–electron repulsions between them is as follows:

Depending on number of bond pairs and lone pairs of electrons the geometry of the molecule can be predicted.

The number of other atoms and the number of lone pairs of electrons in the given possibility are as follows:

The geometries of the molecules are as follows:

Ans:

The geometries of the molecules are as follows: