Here's why:

* Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond.

* Oxygen has a much higher electronegativity than lithium. This is because oxygen has a smaller atomic radius and a greater nuclear charge, which means its nucleus attracts electrons more strongly.

You can find a table of electronegativity values to confirm this. Oxygen typically has an electronegativity of around 3.44, while lithium has an electronegativity of around 0.98.