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The density of copper at room temperature is 8.94 g/cm-3. It has the symbol Cu and the atomic number 29. It is a very workable metal with very high thermal and electrical conductivity. Pure copper is extremely soft and malleable. It is reddish-orange in color. It is frequently used to conduct electricity in the construction industry a building material and as a component in metal alloys.
The low density of copper made it an ideal element to form tools in ancient civilizations. Copper metal and alloys have been used for at least 10,000 years and has been smelted since 5,000 B.C. Copper compounds are usually found as salts of, which give blue or green colors to minerals such as turquoise and have been used widely as pigments. Copper structures and statues corrode and have characteristic green patina.
Copper ions are soluble in water. In low concentrations they act as a bacteriostatic substance, fungicide, and wood preservatives. In larger amounts, copper salts can be poisonous to higher organisms; however, the copper ion is an essential trace nutrient to all plant and animal life in low concentrations. It functions as a co-factor in many enzymes.
Most copper ore is mined as copper sulfides from large open pit mines. The mines tap porphyry copper deposits that contain 0.4 to 1.0% copper. The average amount of copper found within crustal rocks is approximately 68 ppm by mass. Chile is currently the top producer of copper followed by the USA, Indonesia and Peru. At one time Sweden produced 75% of the copper used in Europe and based their currency(the most valuable at the time) on copper. 95% of all of the copper ever mined and smelted has been extracted since 1900. As with many natural resources, the total amount of copper on Earth is vast (about 5 million years worth at the current rate of extraction), but only a tiny fraction of this is economically viable with present-day technology. Estimates of existing copper reserves available for mining vary from 25 years to 60 years.
The density of copper made it the first metal widely used by man and its physical properties have kept it in wide spread use for 10,000 years. As readily available reserves dwindle, the metal becomes more expensive and mining companies seek innovative ways to extract it. Soon it may be more expensive than gold.
We’ve also recorded an entire episode of Astronomy Cast all about the Atom. Listen here, Episode 164: Inside the Atom.