There is also an excellent series of lessons in Khan Academy worth working through: HERE
I really like this guy's video too:
In class, we were also asked to work on a past NCEA question: Discuss the shapes and bond angles in NOCl and H2S (the Lewis Dot Diagrams were provided in the question):
The Lewis diagram for NOCl shows there are three regions of electron density around the central atom (N). This means the electron cloud has a trigonal planar shape with bond angles of 120°. However, as there are only two atoms bound to the nitrogen atom (O & Cl), this is a bent molecule. Due to the repulsion of the lone pair of electrons on the nitrogen atom, the bond angle would be slightly lower than 120°.
The Lewis diagram for H2S shows there are four regions of electron density around the central atom (S). This means the electron cloud has a tetrehedral shape with bond angles of 109.5°. However, as there are only two atoms bound to the sulfur atom (H in both cases) this is a bent molecule. Due to the repulsion of the two lone pairs of electrons on the sulfur atom, the bond angle would be slightly lower than 109.5°.
The Lewis diagram for NOCl shows there are three regions of electron density around the central atom (N). This means the electron cloud has a trigonal planar shape with bond angles of 120°. However, as there are only two atoms bound to the nitrogen atom (O & Cl), this is a bent molecule. Due to the repulsion of the lone pair of electrons on the nitrogen atom, the bond angle would be slightly lower than 120°.
The Lewis diagram for H2S shows there are four regions of electron density around the central atom (S). This means the electron cloud has a tetrehedral shape with bond angles of 109.5°. However, as there are only two atoms bound to the sulfur atom (H in both cases) this is a bent molecule. Due to the repulsion of the two lone pairs of electrons on the sulfur atom, the bond angle would be slightly lower than 109.5°.
