Oxidation involvesLoss of electronsGain of electronsIncrease in the valency of negative partDecrease in the valency of positive part

Oxidation is a chemical process that involves the following:

1. Loss of Electrons: In oxidation, an atom, ion, or molecule loses electrons. This is often associated with the reaction of a substance with oxygen, hence the name 'oxidation'. For example, when Sodium (Na) reacts with Chlorine (Cl), Sodium loses an electron to become Na+.

2. Increase in the Valency of Negative Part: As the atom or molecule loses electrons, the valency of the negative part (anion) increases. Valency is the combining power of an element. It is equal to the number of electrons an atom of the element will lose, gain, or share when it combines with other atoms.

3. Decrease in the Valency of Positive Part: Conversely, as the atom or molecule loses electrons, the valency of the positive part (cation) decreases.

Please note that the gain of electrons is not involved in oxidation; it is a part of reduction. In redox reactions (reduction-oxidation reactions), one substance is oxidized (loses electrons), and another is reduced (gains electrons).