VSEPER Shape?

Question

How can you determine the shape if an atom has a triple bond and a single bond? What about if it has a double bond and a single bond?

Answer 1

You treat the multiple bond like a single bond with higher electron density.
So if you have a C atom with a triple and a single bond, you treat it like having two single bonds. There are no lone pairs, thus the repulsion is such that the angle is 180 deg and thus the geometry is linear.
If you have a C atom with a double bond and two single, you have 3 bonds and no lone pairs, thus the geometry is planar trigonal. Since the double bond has higher electron density than the single, the double bond-single bond repulsion is greater than the single bon-single bond and thus the deviation of the ideal shape for 3 equivalent bonds (bond angle 120 deg) is such that the 2 angles double bond-single bond are a bit larger than the single bond -single bond.
For other atoms like N, S you have to take into account the lone pairs but also the possibility to have resonance structures. In order to have resonance the atoms that participate in the delocalized bonds must be on the same plane.