Some atoms fill their outermost energy level by gaining or losing electrons. Cations lose electrons and have an excess positive charge, e.g . For every anion there must be a cation. In a polar solvent like water, however, the attraction between ions is relatively weak and the ions move about separately surrounded by water molecules. Oxidation and Reduction A chemical reaction that involves the loss of one or more electrons from one molecule is called oxidation .
Reduction is the complementary gain of electrons by another molecule.
In sugars, the C-H bonds are a great source of energy for living cells because they can be oxidized and the energy they release can be harnessed to fuel all sorts of activities in the cell. Back to Dr. Hensley's 181 Links .