Electronegativity oF NH3 and NH4+

Electronegativity is a chemical property that describes the ability of an atom to attract electrons towards itself in a covalent bond. therefore, the electronegativity of ammonia NH3 and ammounium ion NH4+ is different. NH4+ is notvery stable in aqueous solution because it can easily attract a electron and lose a hydrogen to form NH3. In the other hand, NH3 is difficult to attract an electron because it is stable. It can lose electron when it is combined with hydrogen only.

electronrgativity is just describe a certain atom rather describe a certain compound.
so, I think you should focus on the polarity of the compound.

Electronegativity is a measure of the ability of an ATOM to attract bond-pair electrons.

However, NH3 is a molecule and NH4^+ is a polyatomic ion. Therefore, the terms "electronegativity of NH3" and "electronegativity of NH4^+" are UNDEFINED.