Question

What is the valency of oxide?

Answer 1

Valency of an atom is defined as it combines property i.e. the ability atoms to involve in bonding by losing, sharing or gaining electrons and forming bonds with other atoms. An atom may gain or lose electrons to form charged species and form ionic bonds whereas some share the electrons with others to form covalent bonds.

Complete step-by-step answer: Before going into the solution of the question, first we have to discuss a few terms which will give us better understanding on finding the valency of oxide.
First let us discuss the structure of an atom. We know that an atom has a nucleus and the electrons are distributed outside the atom. The size of the nucleus is negligible if we compare the size of the atoms, the atom has a radius of about ${{10}^{-10}}m$ whereas the radius of nucleus is ${{10}^{-15}}m$. The nucleus has positive charge since protons are present in them and neutrons are also present in the nucleus. The mass of the nucleus is considered as the mass of the atom. Protons and neutrons of an atom are collectively called nucleons. The electrons are present outside the nucleus to make the atom electrically neutral and stable.
Now let us discuss atomic number and mass number. Atomic number is a unique number for the element which is equal to the number of protons or number of electrons present in the atom. And the mass number or atomic mass is the total mass of nucleons or say the sum of the number of protons and neutrons in an atom. Atomic number is denoted as Z and atomic mass as A.
Next comes the valency of the atom. The valency of an atom is always referred to as the combining ability of the atom. The number of bonds an atom can form with other atoms. In bonding valence electrons of an atom is involved hence the valency of an atom depends on the number of valence electrons present in an atom.
To form bonds some atoms gain electrons and form negatively charged ions called as anions and some atoms lose their electrons to form positively charged ions which are known as cations.
Oxide ion has the formulae ${{O}^{2-}}$, it is a negatively charged species.
We generally refer to oxide of an element as a chemical compound in which more than one oxygen atom will be present along with other atoms in its composition. Oxide ion along with another metal ion (cation) forms the oxides of that metal. Oxygen has atomic number 6 and 6 electrons, it gains two electrons from other atoms to complete its octet configuration
Hence, the valency of oxide ion is -2.

Note: The isotopes are those species which will have the same atomic mass but different atomic mass, and the difference in mass is due to the difference in the number of neutrons. The number of electrons remains the same, so the chemical behavior will remain the same and hence the valency will remain the same.