∞ generated and posted on 2016.01.26 ∞
Loss of an electron.
Atoms which are highly electronegative are capable of stealing electrons from other atoms. The most prominent stealer of electrons is the oxygen atom. The more oxidized a compound generally the less usable energy associated with it, so therefore the more C-O bonds (carbon to oxygen) and less C-H bonds (carbon to hydrogen) then the less energy that an organism can obtain from a compound.
Oxidation is linked chemically with reduction, where the gain of an electron by one atom is associated with the loss of an electron by another atom. For example, in the formation of the molecule water, H2O, oxygen serves an oxidizing agent, stealing electrons from hydrogen, and thereby becoming reduced while hydrogen atoms serve as a reducing agent, donating electrons to oxygen and thereby becoming oxidized. Water is the most common reduced form of oxygen and oxidized form of hydrogen.