Copper, silver and gold are not active due to their chemical properties, so they have free simple substances in nature.Copper and silver mainly exist in the form of minerals.Gold mainly exists in free state.
Chinese name
Copper group element
Type
Transitional element
chemical property
There are 18 electrons in the secondary layer of the atom
There are 18 electrons in the secondary layer of the atom, whose atomic radius is smaller than that of alkali metals in the same period, and its ionization energy is larger.Therefore, the activity is far less than that of alkali metals, and it is an inactive metal, which decreases in the order of Cu, Ag, and Au. The reason is that from Cu to Au, the atomic radius increases slightly, but the nuclear charge does increase significantly, and the shielding effect of 18 electrons in the secondary layer is smaller, that is, the attraction of effective nuclear charges to valence electrons increases, so the metal activity decreases in turn.Copper sub group elementsThere are+1,+2 and+3 oxidation numbers.The copper minor group element compounds are mostly covalent, because the ions with 18 electron layer structure have strong polarization and obvious deformability, so the elements of this group are easy to form covalent compounds and complexes.
The valence electron configuration of copper group elements is n-1 d ^ 10 n s ^ 1, and the outermost layer is one electron. However, unlike the first sub group, it can form the valence of+1,+2, and+3, with different stability. The characteristic oxidation numbers are: Cu:+2, Ag:+1, Au+3. In addition, copper has+1 valence, silver has+2,+3 valence, and gold has+1 valence.The stability varies greatly due to different conditions.
The common feature of copper group elements is that the oxidation number is+1.However, in acid solution, only Ag+can exist stably, Cu+will be disproportionated, and so will Au+. Only stronger coordination agents such as CN - can form stable complexes with Au.
Add strong base into the salt solution of Cu (Ⅰ) and Ag (Ⅰ) to form MOH typehydroxide。Both are extremely unstable and immediately dehydrated into oxides.Cuprous oxide(red) and silver oxide (black) areCovalent compoundBoth are alkaline.However, the alkalinity of hydroxide is weak, and it is easy to dehydrate to form oxides. From top to bottom, the alkalinity of hydroxide is enhanced;Alkali metal hydroxide is a strong alkali, which is very stable to heat. The alkalinity of alkali metal hydroxide is enhanced from top to bottom.
physical property
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Copper group metals have high density, high melting point, and are excellent conductors with good ductility, especially gold. One gram of gold can draw up to 3 kilometers of gold wire, or press into gold foil about 0.0001 mm thick.The conductivity of Ag is the first, and that of copper is second only to that of silver.
gold
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The positive trivalent is the characteristic valence of gold.Gold trichloride, a dimer, is prepared from Au and chlorine at 473K.It is a plane square structure and dissolves in water to form monohydroxytrichloride alloy acid.This is a strong oxidant that can oxidize sugar and reduce itself to gold sol.
copper
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Univalent copper includes CuCl, CuBr, CuI and CuF (it is recorded that it was made but impure).All cuprous halides are white and insoluble in water.
It is easy to form alloys between copper group metals and other metals. There are many kinds of copper alloys, such as bronze (80% Cu, 15% Sn, 5% Zn), which is tough and easy to cast. Brass (60% Cu, 40% Zn) is widely used as instrument parts. White copper (50-70% Cu, 18-20% Ni, 13-15% Zn) is mainly used as tools.Copper, Fe, Mn, Mo, B, Zn, Co and other elements can be used asMicroelement fertilizer。
