4) What is the difference between tetrahedral bent and trigonal planar bent?

A tetrahedral bent molecular geometry involves four electron pairs including two lone pairs and two bonding groups while a trigonal planar bent molecular geometry involves three electron pairs two bonding groups and one lone pair.

Explanation:

According to valence shell electron pair repulsion theory, the number of electron pairs on the central atom of a molecule influences its shape. It follows that, the shape of a molecule is a consequence of arrangement of valence shell electron pairs. Electron pairs must be positioned as far apart in space as possible.

Electron pairs may be bonding pairs or lone pairs. The repulsion between two lone pairs is greater than the repulsion between a lone pair and a bond pair which in turn is greater than the repulsion between two bond pairs. Hence the presence of lone pairs causes much distortion of the expected molecular geometry of the molecule as predicted by VSEPR theory. This distortion usually leads to the assumption of a bent geometry, depending on the expected geometry of the molecule based on VSEPR theory.

A tetrahedral bent molecular geometry involves four electron pairs including two lone pairs and two bonding groups while a trigonal planar bent molecular geometry involves three electron pairs; two bonding groups and one lone pair. For a bent tetrahedral geometry, the bond angle is much less than 109° while for a bent trigonal planar geometry, the bond angle is much less than 120°.

the atomic mass is the bottom number on the element.

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