chem 23 M10

• Electron transfer is the movement of an electron from one atom to another
• Oxidation state is a useful tool for keeping track of electron transfers especially for transition metals. It is a number assigned to an element in a compound which enables us to describe oxidation-reduction reactions and balancing redox chemical reactions.
• The oxidation state of an atom: • charge that results when the electrons in a covalent bond are assigned to the more electronegative atom • charge an atom would possess if the bonding were ionic
• Compounds of the alkali (oxidation number +1) and alkaline earth metals (oxidation number +2) are typically ionic in nature. Compounds of metals with higher oxidation numbers (e.g., tin +4) tend to form molecular compounds
• In ionic and covalent molecular compounds, usually the less electronegative element is given first. In ionic compounds the names are given which refer to the oxidation (ionic) state. In molecular compounds the names are given which refer to the number of molecules present in the compound.
• An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
• Comprised of two parts: a reduced half and an oxidized half - There is no net change in the number of electrons in a redox reaction. Those given off in the oxidation half reaction are taken up by another species in the reduction half reaction
• Reducing agent: oxidized, donates electrons, oxidation number increases Oxidizing agent: reduced, accepts electrons, oxidation number decreases