Question

Which is the larger ion, fluoride or nitride ion?

Answer 1

The radius of a monatomic ion in an ionic crystal structure is called the ionic radius. Although neither atoms nor ions have sharp boundaries, they are frequently regarded as if they were hard spheres with radii so that the distance between ions in a crystal lattice is equal to the sum of the ionic radii of the cation and anion. The idea may be applied to solvated ions in liquid solutions if the solvation shell is taken into account.

Complete answer:
Depending on the ion's electric charge, it might be bigger or smaller than the neutral atom. When an atom loses one electron to create a cation, the remaining electrons become more attracted to the nucleus, reducing the ion's radius. Similarly, when one electron is added to an atom to produce an anion, inter electronic repulsion increases the size of the electron cloud.
The ionic radius is a variable characteristic of an ion that fluctuates depending on coordination number, spin state, and other factors. Ionic radius values, on the other hand, are sufficiently transferrable to allow for the detection of periodic patterns. Ionic radii, like other forms of atomic radius, grow as you go down a group. Ionic size rises with increasing coordination number for the same ion, and an ion in a high-spin state is bigger than an ion in a low-spin state. In general, ionic radius reduces as positive charge increases and increases as negative charge decreases.
We know that the fluorine atom is SMALLER than the nitrogen atom, with F being 50 pm and N being 65 pm.
We expect that ${{N}^{3-}}$ will be bigger than ${{F}^{-}}$ after reduction. Fluoride has a higher nuclear charge than nitride, and the fact that nitride is three times negatively charged suggests that it will be bigger.
In chemistry, a nitride is a nitrogen compound with a formal oxidation state of three. Nitrides are a diverse group of chemicals with several characteristics and uses. Because it is so basic, the nitride ion, ${{N}^{3-}}$ , is never found in protic solution because it would be protonated quickly. It has an estimated ionic radius of 140 pm. Fluoride is an inorganic, monatomic anion of fluorine with the chemical formula ${{F}^{-}}$, whose salts have an ionic radius of 119 pm and are generally white or colourless.
Hence nitride ion is larger

Note:
Cations have smaller radii and anions have greater radii than their parent atoms due to the loss of electrons from the valence shell in the case of cation, which reduces the shell number, and the addition of electrons in the case of anion, which increases the shell number. This results in a decrease in cation size and an increase in anion size.