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Oxidation number or oxidation state with explained examples

Answer Text:
Oxidation number/oxidation state:
- Refers to the number of electrons an atom loses or gains during a chemical reaction.
- In writing the oxidation number the sign (+ or -) to show gain or loss is written followed by the
number of electrons lost or gained respectively.
Illustration.
- Atoms are electrically neutral and are thus assigned an oxidation state of 0 since the number of
protons in the nucleus is equal to the number of electrons in the energy levels.
- However when atoms react they either lose or gain electrons and thus acquire a new state.
- This new state is a new oxidation state and the atom
thus acquires a new
oxidation number
Examples:

Further examples:

Note: oxidation number (state) and charge of an element.
- Oxidation state is written with the positive or the negative sign coming before the element.
Examples: -2, 3, +1, -1 etc.
- Charge on an element is write as a superscript of the element with the number coming before the
positive are the negative sign
Examples: #Mg^(2+)#,# Al^(3+)#, #Na^(+)#, #Cl^(-)# etc.