Which is more electronegative? o or br

Oxygen is more electronegative.

Explanation:

Electronegativity:

Electronegativity of an atom is its tendency to attract the electron to wards it self.

Br = 2.98

O = 3.44

Oxygen is more electronegative than bromine thus it attract electron more strongly towards itself as compared to bromine.

when an more electronegative atom combine with less electroneagtive atom partial charges are created upon them. e.g

In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive.

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.