> See also: > - [[The Periodic Table]] # Oxidation and Reduction Despite its name, **oxidation does not require oxygen to occur** **Oxidation** is defined as the *loss of electrons* in a molecule. - The removal of hydrogens - Increase in [[electronegativity]] of neighboring atoms (making electrons less likely to remain near the central atom) - **Reduction** is defined as the *gain of electrons* - The addition of hydrogens (which has a low electronegativity) - Decrease in electronegativity of neighboring atoms --- Similar to acids and bases, the acceptor and donor of a half reaction are referred to as a conjugate redox pair When describing a reaction as a reduction or an oxidation reaction, it is typically referring to the changes made to the substrate. - Something being oxidized implies that something had to act as the “oxidizing agent” and become reduced in the process (and vice versa) ![[Pasted image 20231017202441.png]] ## Oxidation Numbers An **oxidation number** (aka the *oxidation state*) represents the “ownership” of electrons compared to the neighboring atoms. 1. The oxidation number of an atom in an elemental substance is zero. In fully [[Chemical Bonds|covalent]] compounds the oxidation number should be 0 as all of the electrons present are being shared equally. In ionic compounds, electrons are being lost or gained, causing the oxidation number for the individual atoms in a compound to change. --- > [!important] Calculating Oxidation Numbers > Go through every atom connected to the atom in question > - If the electronegativity is *identical* to the parent atom, *+0* > - If the electronegativity is *less* than the parent atom, *-1* > - If the electronegativity is *more* than the parent atom, *+1* > > The oxidation number of an element in it’s free (uncombined) state is zero. **Ex:** $Al(s) or Zn(s)$ > >This is also true for all elements found in nature as diatomic. **Ex:** $O_2$ a - The oxidation number of an element in its free (uncombined) state is zero - Ex: Al(s) & Zn(s) - This is also true for elements found in nature as diatomic (two-atom) elements - The oxidation number of a mona ## Determining