Question

Write two differences between \[{{O}_{2}}\] and \[{{O}^{2-}}\].

Answer 1

Hint: When we are just talking about the element, then using the symbol is pretty self-explanatory. But sometimes we need to describe how the element appears in the word or in chemicals which may be different from its elemental form.

Complete step by step solution:

Oxygen atom contains a total number of 8 electrons out of which only 6 of these are in the outermost shell or orbital and the electronic configuration of an oxygen atom is \[1{{s}^{2}}2{{s}^{2}}2{{p}^{4}}\]. Elements always prefer to have their outer shells completely filled and obtain noble gas configuration and they want this state as easily as possible. In the case of Oxygen, it is easier to gain 2 electrons rather than losing 6 electrons. Now, let’s come to our question.

When we are just talking about the element, then using the symbol is pretty self-explanatory. But sometimes we need to describe how the element appears in the world or in chemicals which may be different from its elemental form.

\[{{O}_{2}}\]	\[{{O}^{2-}}\]
Molecular oxygen (O2) is composed of two oxygen atoms bound to each other via covalent chemical bonding which makes it a diatomic molecule.	\[{{O}^{2-}}\] is an ion of oxygen, to be more precise, a cation. It is formed when an oxygen atom gains two electrons.
Atomic oxygen has a total of eight electrons. Therefore, an oxygen molecule (\[{{O}_{2}}\]) has 16 electrons which is two times eight ant net charge of 0.	This oxygen ion has now 10 electrons and only 8 protons, giving the ion a net charge of -2.
Therefore, we write the 2 as a subscript of O, indicating two molecules of oxygen.	Symbolically, we can represent this oxygen ion as \[{{O}^{2-}}\]with a superscript -2 indicating the negative charge

Note: Both of them have different electronic configurations also.
Molecular electronic configuration of \[{{O}_{2}}\] molecule is
\[{{({{\sigma }_{2s}})}^{2}}{{({{\sigma }_{2s}}*)}^{2}}{{({{\sigma }_{2p}})}^{2}}{{({{\pi }_{2p}})}^{4}}{{({{\pi }_{2p}}*)}^{2}}\]
Electronic configuration of \[{{O}^{2-}}\] ion is
\[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}\]