Final answer:
In redox reactions, oxidation numbers are used to track electron transfers, with atoms being oxidized when they lose electrons and reduced when they gain electrons; the total number of transferred electrons equals the difference between the atoms' initial and final oxidation states.
Step-by-step explanation:
In redox (oxidation-reduction) reactions, the transfer of electrons between atoms is tracked using oxidation numbers. When an atom loses electrons, it is oxidized; when an atom gains electrons, it is reduced. It is crucial to apply specific rules for assigning oxidation numbers to correctly determine what is being oxidized and reduced in a redox reaction.
For example, in the reaction 2Rb + MgCl₂ → 2RbCl + Mg, Rb goes from 0 to +1 (it loses one electron and is oxidized), while Mg goes from +2 to 0 (it gains two electrons and is reduced). In this process, two electrons are transferred from Rb to Mg. To confirm a redox reaction, oxidation numbers are calculated before and after the reaction for each atom to determine any changes.