Oxidation

Okay! So, now let's look a little bit forward onto chemical reaction.

Our first topic is Oxidation.

Back in the days, chemists believed that oxidation was any reaction that occurred between any atom or compound with a molecular oxygen. 

However, after many and many years of study and analysis, it was learned that same reaction between atoms or compounds with other elements have similarities with those reaction involving oxygen. 

So the scientist came out with another definition for oxidation, which is the loss of electrons by an atom or an ion.

For example, when Mg(s) reacts with Cl2(g), our little buddy Magnesium atom loses electrons, becoming a cation. We can say, therefore, that Magnesium got oxidised.