If you look around yourself, you will find a variety of objects. Have you ever though as to how and with what these objects around us are made of? Everything around us is made up of one or more of the 112 known elements. A scientist named Lavoisier broadly classified these elements into metals and non-metals, by studying their properties. There are about 90 metals and all metals have certain common physical and chemical properties. Non-metals also have certain common physical and chemical properties.
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Physical Properties of Metal
1. Metals have a metallic lustre.
Collect some pieces of some common metals, like iron, copper, aluminum and magnesium. Observe their appearance and how they reflect light. The reflection is different for each metal. The shine of light on a metal is called metallic luster.
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2. Metals are generally hard, though some are soft.
Most of them are hard like iron, aluminum, etc, though potassium and sodium are soft and can be cut with a knife.
3. Metals are malleable.
This means that the metals can be hammered into sheets. Have you seen a blacksmith working in his foundry? He beats iron metal into thin sheets for making various implements. Metals like aluminum, gold, sliver are hammered into sheets and used for making utensils and ornaments.
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4. Metals can be drawn into wires, i.e. they are ductile.
We all have seen electric wires made of copper and aluminum. Iron wires are used for fencing. Goldsmiths make gold thread by drawing gold into fine wires. This property of metals is called ductility. We say gold, silver, copper, aluminum and iron and ductile.
5. Metals are good conductors of heat.
We use vessels made of aluminum and copper for cooking because they are good conductors of heat. Try holding one end of an iron rod with the other end over fire. After a little time you can feel the heat at your end of the rod also. This shows that heat is conducted by the iron rod. But, different metals take different times to conduct heat.
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6. Metals are good conductors of electricity.
Metals are generally good conductors of electricity. To prove this, set up a simple electric circuit. Hold a piece of copper metal between metallic crocodile clips. Notice that the bulb glows. Now repeat the experiment with a piece of iron, zine, nickel, etc.
7. Metals have high density.
8. Metals are sonorous.
Drop two spoons, one made of steel and the other made of iron. Observe the sounds they make. Which of them produces a ringing sound? All metals produce a ringing sound, i.e. all metals are sonorous.
9. Metals generally have high tensile strength.
Tensile strength means the greatest longitudinal stress a substance can bear without tearing apart. Try pulling both ends of a piece of paper or plastic. It will easily tear and break. Now try to break iron, copper or aluminum wire. They do not break. It shows that meats are strong.
10. Metals are usually solids.
Mercury is a metal in liquid from at room temperature.
11. Metals in generally have high melting points.
For example, the melting point of aluminum is 659.7˚C, of copper 1084˚C and of Iron 1535˚C.