More electronegative?

[Lelija Kazlauskas 3J]

Why is oxygen more electronegative than chlorine? They're both in an awkward spot on the periodic table.

[Elena Bell 1C]

Electronegativity decreases as you go down the groups. Oxygen is higher on the periodic table than chlorine, so its electronegativity is higher.

[Hannah Lee 2F]

O has only one e- less than F, giving it a high nuclear charge and a greater ability to attract e-. On the other hand, Cl is below F with an entirely new shell of valence e- added to it, which decreases the nuclear charge experienced by outer e- and decreases its ability to attract e- compared to the O atom.

[kevinolvera1j]

IIRC Oxygen is the second most electronegative element, second only to Fluorine. When both of these elements fill their valence they have the very stable configuration of neon. While Chlorine is closer to filling its octet than oxygen is, its valence electrons are also farther from its nucleus than they are in oxygen.