Kim Owens, age 13, of Helena, Mont., for her question:
WHAT EXACTLY IS METAL?
Metals are defined by chemists as those elements which, when in solution in a pure state, carry a positive charge and seek the negative pole in an electric cell.
When a chemist wants to find out whether an element is metallic or non metallic, he conducts what is called an electrolysis test. This test consists of dissolving the element in acid and running an electric current through the solution.
In the test, if the element is metallic, the tiny atoms which make it up will show a positive charge. This means that when electricity is run through the solution, the atoms will seek the point where the electricity enters the solution, or the negative pole.
Most metals have a silvery color. They are shiny and usually heavier than water. Most of them conduct heat and electricity very well.
Many of the most important metals can be hammered into thin sheets and are described as malleable. They also can be drawn out into wires and are called ductile.
A few metals, such as gold, copper and strontium, are colored. Some metals are not malleable and ductile but are so brittle that they break quickly when worked. Calcium is an example of such a metallic element.
Metal forms a large part of the earth on which we live. The earth's crust is said to be made up of about eight percent aluminum, five percent iron and four percent calcium. The core of the earth is much heavier than the crust and scientists believe that it is made up mainly of nickel and iron.
Scientists also say that they believe more of the heavy metals, such as gold, lead and mercury, lie in the core than near the surface.
Certain alloys, or combinations of metals with other metals, are also called metals. Among these are bronze, bell metal, gun metal and type metal.
Alloys and metals that do not contain iron are referred to as nonferrous metals.
Some substances such as boron and selenium are called non metals. Chemically they are not metals, but they have one or more of the physical properties of metals.
Ancient man used many native metals. Gold was used for ornaments, plates and utensils as early as 3500 B.C. Silver was used as early as 2400 B.C.
Since about 1000 BC., iron and steel have been the chief metals for construction.
Today, because the best iron ore supplies for steelmaking are being exhausted, metallurgists are substituting aluminum for steel in many cases. The supply of aluminum is almost unlimited.