After electrons are given, they are oxidized into positively charged neutral atoms, such as iron filings, zinc powder, etc.;
Negatively charged atoms are oxidized to positively charged atoms after giving electrons. For example, the boron element in sodium borohydride has a negative valence of 5, which can reduce mercury ions to metallic mercury under alkaline conditions, and at the same time it is oxidized. Into positive trivalent.
A metal or non-metal positively charged atom is oxidized to a higher positively charged atom after giving an electron. For example, the divalent iron ion Fe2+ in ferrous sulfate and ferrous chloride is oxidized to trivalent iron ion Fe3+ after giving one electron; the tetravalent sulfur in sulfur dioxide SO2 and sulfite SO32- gives two electrons Later, it is oxidized to hexavalent sulfur, forming SO42-.