Copper by Amanda Garcia |
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| A mole is a furry little rodent that dines upon the roots of your grass
and other plants. Well that is the mole, but we are talking about a different kind here. A
mole is a mathematical formula for the amount of atoms in a given substance. Unlike other
forms of measurement, it is very hard to comprehend how much matter is in a mole.
Avogadro's number is one of the constants of chemistry. It allows us to calculate the
amount of pure substance, which happens to be called a mole. It also makes a possible
determination of how much heavier a simple molecule of one gas is than that of another,
and as a result the relative molecular weights of gases can be determined by comparing the
weights of equal volumes. Did You Know? 1. If Avogadro's number of sheets of paper were divided into a million equal piles, each pile would be so tall that it would stretch from the Earth to the Sun. 2. Avogadro's number of pennies placed side by side would stretch for more than a million light years. 3. Counting at the rate of one atom per second, for 48 hours a week, it would take the entire population of the world 10 million years in order to reach Avogadro's number. Copper The element copper is reddish metal at the head of group IB in the periodic table. Its symbol is Cu. Its atomic number is 29 and its atomic weight is 63.546. Copper was the first metal used by humans approximately 7,000 or more years ago. The discovery of the metal dates from prehistoric times. The name copper is derived from the Latin Cuprum, "copper" from the earlier Latin Cyprium, "Cyprian Metal." Copper today is mined in many parts of the world; the largest producers at present are Chile, Peru, Poland, and the United States. More than 160 minerals containing copper are known. Copper constitutes 70 parts per million of the Earth’s Crust. Eleven isotopes of copper are known; two of them are not radioactive and another two occur with natural abundance. Copper melts at 1,083.4 degrees Celsius and boils at 2567 degrees Celsius. Copper has a density of 8.96 at 20 degrees Celsius. Copper has a hardness of 3, takes on a metallic luster, has a cubic crystal structure, and is a good conductor of heat and electricity. The amazing feature of copper is their resistance to chemical attacks. When copper is slowly attacked by moist air, its surface gradually becomes covered with a blue-green cover that consists of basic sulfate. At about 300 degrees Celsius copper is covered with a black coating which is Copper (II) oxide.
Copper mixes well with many elements, and more than 1,000 different alloys have been found several which are technologically significant. The best known alloy of copper is brass. Another useful alloy is nickel silver. It is used for silver-plating items such as jewelry and tableware. Copper is a trace element essential to the healthy life of many plants and animals. The normal diet of humans includes between 2-5 milligrams of copper per day, which exceeds the body maintenance requirements of 2 milligrams. The hereditary disease known as Wilson’s disease is associated with the increase in the copper content in almost all tissues, particularly the brain and liver. Albino mammals lack the normal form of the copper that contains tryosinase enzymes, which helps with the pigment. Copper can be toxic in large quantities, especially in smaller organism such as fungi and algae. |
