Question

What is the name of LiH?

Answer 1

Hint: The naming of compounds is done according to the norms set by IUPAC. The naming is done in such a way that the positive ion which is the cation is named first, while the negative ion that is anion is named after the cation. LiH consists of lithium and hydrogen as constituent atoms.

Complete step by step answer:
The naming of any compound is done according to the IUPAC rules. This states that the name of the positive species which is the cation is named first, and then the negative species, anion is named. Any ion becomes a cation by donating the electrons, while an ion becomes an anion by gaining electrons. Also the ion which has a negative charge is more electronegative.
We have been given the formula of LiH that has lithium and hydrogen. We know that Li has the atomic number 3 with electron configuration, $Li=1{{s}^{2}}2{{s}^{1}}$ , while hydrogen with atomic number 1 has configuration, $H=1{{s}^{1}}$. As lithium has a larger size than hydrogen, it is electropositive, while hydrogen being smaller in size is electronegative and gains electrons from the lithium cation.
This implies that hydrogen is the anion, and lithium is the cation. Hydrogen when present with a negative charge (anion) has a name given, ‘hydride’. So, the name of LiH is lithium hydride.
Hence, LiH is lithium hydride.

Note:
In the formula, the anions are written after cations, so Hydrogen will automatically be the anion, as written on the right side. Electronegativity of any element is the tendency to attract the electrons, hydrogen is more electronegative in this molecule due to its small size. This trend can also be seen in the periodic table as electronegativity decreases down the group, and lithium is below hydrogen.