Question

why potassium is oxidized more quickly than sodium

Answer 1

Potassium lies lower in Group-1 of the alkali metals than sodium, it has one more shell than sodium and has a much larger atomic number, the greater number of shells tends to dominate over the fact that the positive nuclear charge is greater, this leads to a larger atomic size in potassium as compared to sodium, so the ionization potential of potassium is more than that of sodium, potassium loses an electron more readily and easily than sodium, it is more metallic and more chemically reactive, hence it is oxidised more easily as compared to Sodium.