Question

How can the oxygen atom become an ion with a charge of -2?

Answer 1

Hint: The answer here is based on the general concept of the atom. Write the electronic configuration of an oxygen atom and then by finding the electrons required to complete the octet rule, the required answer can be approached.

Complete step by step solution:
- As we all know that atomic number denotes the total number of protons present in the nucleus of an atom.
- As we know that oxygen atom is having atomic number eight. It is found that the number of protons is equal to the atomic number. This means that the nuclei of all oxygen atoms have eight protons. It is found that a neutral oxygen atom will also have eight electrons.
- As we know that when oxygen forms a bond then it pulls the electron density of the bond closer to oxygen and away from the other element. This leads oxygen to have a negative charge and another atom a positive charge. It is found that oxygen is having the electronic configuration as:
$1s^{2}2s^{2}2p^4$
- We can see that this leaves oxygen with two p orbitals and it needs two more electrons to complete the octet and these unpaired electrons can form two bonds.
- And as we know that each of these bonds creates a negative one charge giving oxygen a charge of -2.

- Hence, we can conclude that there are 8 protons and 10 electrons in an oxygen ion that has a -2 charge and oxygen atom becomes an ion with a charge of -2 by the transfer of electrons.

Note:
- We should note that the total number of neutrons present in the nucleus is equal to the difference between the atomic number and the mass number of an atom.
- As we know that the mass number of an atom is basically equal to the addition of the protons and neutrons that are present in the nucleus.