Chemistry Problems

Question

What do the properties of a molecule depend on?

What does VSEPR stand for and what does the theory state?

Why are molecules such as H2, HCl and BeF2 linear in shape?

What is the shape and the bond angles for BF3, boron trifluoride and CH4, methane?

What does VSEPR postulate about the lone pair of electrons on the central “N” atom in ammonia, but what does our description of the shape of the molecule only refer to?  

Answer 1

VSEPR stands for valence shell electron pair repulsion and this theory states that electron pairs repel each other to minimize repulsion between electron pairs.H2, HCl, and BeF2 are linear in shape because they reduce repulsion by arranging themselves linearly and an angle of 180°is present between them.

The structure of BF3 is trigonal planar with an angle of 120°whereas the geometry of methane is tetrahedral and the angle between them is 109.5°.

The presence of a lone pair-bond angle will deviate because lone pair repel other electrons more strongly than bonding pair.

In the case of ammonia, the lone pair-bond pair repulsion is more than the bond pair-bond pair repulsion and therefore the angle between ammonia is 106.7°.

Properties of molecules depend on their shape.