Question

Why is the formal charge of N in NH2 a negative?

1. Nitrogen has a higher electronegativity than hydrogen.
2. Nitrogen is in a group with a higher ionization energy.
3. Nitrogen is sharing electrons with hydrogen.
4. There are more electrons around nitrogen than it prefers to have based on its usual valence.

Answer 1

The formal charge of nitrogen in the NH2 ion is negative because nitrogen has one additional pair of unshared electrons, giving it a total of one more electron than proton.

Step-by-step explanation:

The formal charge of N in NH2 is negative because of the way nitrogen shares its electrons with the hydrogens and the number of electrons nitrogen possesses. A neutral nitrogen atom typically has five valence electrons. When it forms the NH2 ion, it shares these electrons with two hydrogen atoms, sharing one pair of electrons with each hydrogen through covalent bonds.

The structure of the NH2 ion typically shows nitrogen with one additional pair of unshared electrons, which means that nitrogen effectively has one more electron than it has protons, giving it a negative formal charge.

The electronegativity of nitrogen is higher than that of hydrogen, which means that nitrogen has a tendency to attract electrons more strongly than hydrogen, reinforcing the negative charge on nitrogen within the NH2 ion. Nitrogen does not acquire a partial positive charge in this ion; rather, it maintains a negative charge due to the aforementioned reasons, contrasting from the statement made in option a.