Chemical elements
    Physical Properties
      Valency and Ions
      Weight of Copper
    Chemical Properties
    Cuprous Compounds
    Complex Copper Compounds
    Cupric Compounds
    PDB 1a2v-1bxu
    PDB 1bxv-1fwx
    PDB 1g3d-1j9t
    PDB 1jcv-1mfm
    PDB 1mg2-1paz
    PDB 1pcs-1sii
    PDB 1sjm-1w6w
    PDB 1w77-2afn
    PDB 2ahk-2dv6
    PDB 2dws-2ggp
    PDB 2ghz-2mta
    PDB 2nrd-2vm3
    PDB 2vm4-2yah
    PDB 2yam-3bkt
    PDB 3bqv-3fyi
    PDB 3g5w-3mie
    PDB 3mif-3t6v
    PDB 3t6w-9pcy

Copper Valency and Ions

Copper is usually considered to exhibit univalency in the cuprous compounds and bivalency in the cupric compounds. Its univalency in the cuprous compounds accords with the position of the metal in the periodic system, and is exemplified by the resemblance of the cuprous halides to the halides of silver and univalent gold, and also by the isomorphism of cuprous sulphide and silver sulphide. The bivalency of the atom in the cupric compounds is in agreement with the properties of many of its derivatives, a typical example being the isomorphism of cupric sulphate with the sulphates of ferrous iron, zinc, magnesium, and manganese.

Besides these two main classes of copper compounds, there appear to be other types of copper derivatives, among them oxides of the formulae Cu4O, Cu3O, Cu2O3, and CuO2. The cuprous ion, Cu, corresponds with the cuprous compounds, which are colourless in aqueous solution. The cupric ion, Cu•• corresponds with the cupric compounds, which have a blue, green, violet, yellow, or brown colour in solution.

The cupric ion displays a characteristic power of forming complex derivatives with ammonia and substituted ammonias, an example being the cupric ammonium hydroxides. A great number of other complex derivatives are derived from cuprous or cupric ions. In certain of these compounds both kinds of copper ions are present simultaneously, examples being the complex cupric-cuprous cyanides and sulphites. The cupric ion is characterized by a tendency to form basic salts, a great number having been described.

Both cupric and cuprous salts act as oxidizers, the cupric derivatives being reduced to the cuprous or metallic condition, and the cuprous compounds to metallic copper. Alkaline solutions of cupric salts are employed in oxidation-processes in organic chemistry.

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