Saturday, April 20, 2013

Ancient Elements

Only about a dozen elements were known to the people living in ancient civilizations.

  • Copper beads dating from about 6000 B.C. have been found in Turkey.
  • A lead statuette found in an Egyptian temple dates from around 3800 B.C. and golden artefacts have also been found in ancient Egyptian tombs.
  • Silver was used by the ancient Greeks and Romans to prevent infection, and was used as an early form of currency.
  • There is evidence of the systematic production of iron in Turkey around 2000 B.C. for use in tools and weapons.
  • Carbon, in the form of diamonds, was also known in the Ancient world, but, carbon in the form of charcoal was far more important to these early people because it could be used in the production of copper, tin, and therefore bronze (an alloy of copper and tin).
  • Sulfur was also known to the Ancient Egyptians and Greeks, who used it as a medicine.
  • The ancient Chinese, Indians and Egyptians also knew about mercury, using it in ointments and cosmetics.
  • Before 1000 B.C., Indians were extracting zinc from its ores. Ornaments containing 80% or more of zinc have been found.
  • During the Bronze Age (an earlier period than the Iron Age), arsenic was included in bronze to make the alloy harder. Ancient people understood that they could produce arsenic by heating certain substances (which we would now call arsenic sulfides and oxides).
  • Antimony was used in cosmetics in the Ancient world, notably by the Egyptians who used it around their eyes (known as kohl).
  • Chromium has been found in ancient Chinese artifacts. The weapons the Chinese Terracotta Army carry are coated in chromium oxide and date from around the 3rd century B.C.
In fact, these were really the only elements known  until the 17th century A.D.
Today we know of over a 100 elements.
Chemistry has come a long way in the last few hundred years!

Further Reading:
History of the Elements
Metal Extraction Concepts
Periodic Table
Metals and Non-metals
Pure Substances and Mixtures

Suggested Study Questions:
  1.  Find each of the elements mentioned above on the Periodic Table.
  2. Draw up a table of the name and chemical symbol for each of the elements mentioned above.
  3. Draw up a table classifying each of these elements as metals, non-metals or semi-metals (metalloids).
  4. Name a mixture mentioned in the article above.
  5. Name a compound mentioned in the article above.
  6. There are only 3 metallic elements that are not a "silvery" colour. One of these is cesium (or caesium), but if the sample of cesium is very pure it loses its golden colour. Name the other two non-silvery metallic elements.
  7. Explain why you often find weapons like swords made of iron, but you never find functional weapons made of gold.
  8. Explain why you find ornamental weapons made out of gold, but rarely out of zinc.
  9. Ancient people could have produced mercury by heating cinnabar (mercury(II) sulfide). The cinnabar decomposes, producing liquid mercury and sulfur. Write a word equation for the decomposition of cinnabar.

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