The density of cast iron, like the density of all objects, depends on the environment in which it is located and its current temperature. At room temperature, cast iron's density is about about 7.2 grams per cubic centimeter. This makes cast iron a fairly dense substance, but one that is still far less dense than nickel, copper, silver, gold and even pure iron itself. Many people think of iron as
. a very heavy metal, but in reality, many common metals are much heavier and more dense than iron. Gold, for example, is nearly three times more dense, lead is over 50 percent more dense and silver is even about 40 percent more dense than iron. Near its melting point around 2500 degrees Fahrenheit, the density changes to lower than 6.8 grams per cubic centimeter. Density is found by dividing the mass of an object by its volume, and volume changes based on temperature, pressurization, and certain other factors. Cast iron is not pure iron, but rather an alloy which includes carbon, manganese, sulfur and other impurities that are not fully drawn out through smelting, which is the process of melting iron ore, which is the natural, oxidized form of iron integrated with other minerals from Earth's crust, to separate the metal from the slag. The density of cast iron is slightly lower than pure elemental iron because of these impurities.The atomic number of iron is 26, which means an atom of iron has 26 protons in its nucleus. This number is not affected by environmental factors. The unique qualities and impurities of cast iron make it stronger than pure iron and more resistant to rust, although it is brittle, as well. Regardless, the lowered melting point, lighter compound, resistance to oxidation and warping make this an alloy with hundreds of industrial and commercial applications. More reference links: http://www.simetric.co.uk/si_metals.htm http://www.matpack.de/Info/Nuclear/Elements/density.html
