If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom, the structure The central X atom is single bonded to two Y atoms, which are 180 degrees apart. The X atom has two lone pairs. could be abbreviated as XY2Z2.

Electron geometry - Tetrahedral

Molecular geometry - Bent

Bond angle - <<109.5°

Explanation:

According to the Valence Shell Electron Pair Repulsion (VSEPR) Theory, the shape of a molecule depends on the number of electron pairs present bon the central atom of the molecule. The electron pairs orient themselves as far apart in space as possible to minimize repulsion between electron pairs.

However, the repulsion between all electron pairs is not the same. Lone pairs cause more repulsion around the central atom than bond pairs. Hence lone pairs tend to distort the molecular structure away from that predicted on the basis of Valence Shell Electron Pair Repulsion Theory.

Considering XY2Z2, there are four electron domains, two bond pairs with bonding groups at 180° apart and two lone pairs. Based on VSEPR theory, a tetrahedral shape is expected with a bond angle of about 109°.

The presence of two lone pairs distorts the observed molecular geometry to a bent shape with bond angle <<109°, hence the answer above.