What is electronegativity, and how does it affect interactions between water molecules?

What is electronegativity, and how does it affect interactions between water molecules?

Answer

Electronegativity is the attraction of an atom for the electrons of a covalent bond.

Because oxygen is more electronegative than hydrogen, the oxygen atom in H2O pulls electrons toward itself, resulting in a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms.
Atoms in neighboring water molecules with opposite partial charges are attracted to each other, forming a hydrogen bond.