Boiling point mainly depends on the size of the molecule (but not, exclusively) and thus, one may say: more electrons → larger molecule → higher boiling point.
However, many other factors play an important role therein, such as:
- shape (branched or spherical molecules have lower boiling point than their isomers.)
- polarity increases the boiling point.
- hydrogen bonding increases the boiling point.
- large heteroatoms such as halogens affect the molecular shape to spherical-like and thus, they significantly decrease the boiling point, in comparison to compounds of the same molecular mass.