1、 Electronic structure and valence state of copper


The atomic number of copper is 29, belonging to IB group in the periodic table. The electron layer arrangement is [ar] 3d104s1, which seems to be similar to [ar] 4s1 of potassium. However, because the shielding effect of d electrons is much weaker than that of P electrons, the top ionization potential of copper is 7.726ev, while the second and third ionization potentials are about 10ev lower than that of potassium. This not only shows that copper is a less vivid metal, which is between base metals and precious metals in the order of metal activity, but also indicates that it may have a variety of valence states


The common habitual states of copper are + 2 and + 1. Cu (Ⅱ) is a relatively stable valence state. Cu (Ⅲ) compounds, such as cuf3, can be formed only under very strong oxidation conditions


2、 Copper compounds and coordination compounds


There are hundreds of copper compounds, among which copper sulfate, copper oxide, cuprous chloride and cuprous oxide are the most valuable for industrial use. Both Cu (Ⅱ) and Cu (Ⅰ) produce many stable coordination compounds. The cooperation of Cu (Ⅱ) and chlorine cooperation of Cu (Ⅰ) are of great significance in hydrometallurgy


When the coordination number of Cu (Ⅱ) is 4, it is generally planar square coordination, and when the coordination number is 6, it is a distorted octahedral configuration. Most of the complexes formed by Cu (I) are linear. Chelating ligands containing nitrogen and oxygen donors, such as salicylic acid oxime, azoin, 8-hydroxy and their substitutes, form a variety of stable chelates with Cu2 +, and generally have a planar square structure. It is on the basis of these ligands that many commercial copper extractants have been developed. The structural characteristics of plane square form the chemical basis of copper separation& nbsp;


3、 Biological function and hygienic standard of copper


Copper containing proteases are found in many organisms, and ceruloplasmin transports oxygen in the plasma of some gastropods, cephalopods and crustaceans. Plasma ceruloplasmin in human serum contains 8 copper atoms, which can catalyze Fe2 + oxidation. A person needs to consume 2.5 ~ 5mg copper every day. There is 100 ~ 200mg copper in the body, mostly in the muscle


Copper salt has strong toxicity to low organisms. The copper content of surface water is limited to 0.1mg/l, and the copper content of industrial wastewater discharge should be less than 1mg / L. Who advocates that the content of copper in drinking water should be 0.05 ~ 1.5mg/l. The threshold of American regular workplace (time weighted uniformity) is: dust 1mg / m3, smoke 0.2mg/m3


4、 Physical properties of copper


The crystal of copper is face centered cubic lattice, the density is 8.96t/m3, the thermal conductivity is 394w / (M & middot; K), and the resistivity is 1.6730 & Mu at 20 ℃& Omega;/ Cm, the temperature coefficient of resistivity at 1 ~ 100 ℃ is 0.00681, the melting point is 1083 ℃, the melting latent heat is 212kj / kg, the specific heat capacity at 20 ℃ is 384j / (kg & middot; ℃), the boiling point is 2595 ℃, and the linear expansion coefficient is 16.5 & times; 10-6 ℃ - 1, tensile strength 23 & times; 104kpa, elastic modulus coefficient (10.2 ~ 12) & times; 104mpa, rigidity modulus coefficient 44000mpa


5、 Standards and uses of copper


China's electrolytic copper complies with the world gb466-82. The London Metal Exchange (LME) class a standard is often used in the world, and the standard of high-purity cathode copper in China is similar


Pure copper is used for wires and electrical appliances. Copper constitutes a variety of alloys of primary industrial value. The alloy of copper and zinc is called brass, and the alloy of copper and tin is bronze, which is used for bearings, switches, heat exchangers, etc. The alloy of copper and aluminum is called aluminum bronze, and the alloy of copper and beryllium is called beryllium bronze. Both have excellent mechanical properties and are used for the manufacture of mechanical and appearance parts. Copper nickel produces white alloy with strong corrosion resistance. It is used for valves, pumps, decoration, etc. Copper and its alloys are mainly used in electric power, machinery, transportation, construction, electronics, appearance and other occupations