Question

What is the charge that results when oxygen becomes an ion?

Answer 1

Hint :Oxygen belongs to the sixth group in the periodic table. So, it contains six electrons in its valence shell. It means that it needs to gain two electrons to obey the octet rule and have a full outer shell of eight electrons. It gains two electrons from other atoms in reactions and forms an oxide ion.

Complete Step By Step Answer:
The element oxygen has six valence electrons. To fill up the valence shell the oxygen atom needs two more electrons. As every electron has a single negative charge, adding two more electrons gives oxygen ion a charge of $2$ . Oxygen needs two electrons to fill its outermost electron shell. Hydrogen has one electron to bond with. So, an oxygen atom needs two hydrogens to bond to in order to complete its shell. After gaining two electrons, the oxygen ion has $10$ electrons and $8$ protons, giving the oxygen ion a net charge of $-2$ . The oxygen ion is generally represented as $O^{-2}$ .
Therefore, the charge that results when oxygen becomes an ion is $-2$ .

Note :
An oxygen molecule consists of two oxygen atoms that have a double bond between each other and share valence electrons. The oxygen ion is formed when the atom of oxygen gains two valence electrons. This results in an oxygen ion with a charge of $-2$ .