How do you write oxidation reduction half reactions?
In redox reactions we invoke electrons as elementary particles, whose LOSS corresponds to oxidation, and whose gain corresponds to reduction. Rather than rabbit on about stuff that may appear in the links, let us consider an actual redox reaction, i.e. the oxidation of ammonia to nitrate ion by metallic zinc.
Now ammonia is OXIDIZED ... from
And as always the difference in oxidation numbers is accounted for by
The overall redox reaction eliminates the electrons....i.e. we takes
And after cancellation...
And again, I stress that while the assignment of oxidation numbers and introduction of electrons as elementary particles may seem a bit fanciful, and abstract, such redox reactions as written do REPRESENT actual chemical transformations, which is of course why we learn how to assign them, and why we utilize them when we write chemical reactions.