Many metal elements can be separated from each other on the basis of physical qualities. These physical characteristics are used to identify metals.
Physical Properties of Metals
- Metals are shiny and they have a special metal lustre.
- Metals are hard but sodium, magnesium are exceptions, these can be cut easily by a knife.
- Metals can be made into thin sheet. Aluminum polythene is used to wrap chocolates and medicines; it is also used to keep the food fresh and war.
- Metal wires are good conductor of electricity. Wires can be made from aluminum and copper. They are used to pass the electricity current.
- Metals are good conductors of heat. These are used in the cooking food utensils.
- Metals are hard and strong, these are used to construct buildings, trains, vehicles, instruments and bridge, etc.
Non-metals are different from metals. They don't have physical properties of metals. Some examples of non-metals are nitrogen, chlorine and oxygen gases, carbon, silicon, etc.
Chemical Properties of Metals
Chemical properties of metals include reactions with air, water and acid. Some metals like sodium, potassium, aluminum, copper, iron are more reactive whereas gold, platinum are less reactive. These metals are found in free form on the earth. Therefore, they are less reactive. Due to reactive properties, oxide, sulphides and carbonates are found in compound form.
Other than pure metals, mixture of metals are also used. These are known as alloy.
Alloys are compounded and homogenous mixtures and are prepared by melting of metals. Some properties of alloy are different from metals. For example, Brass is composed of copper and tin metals. Tin is strong and corrosion resistant but copper is a soft metal. In the same way, iron gets rust easily. However, when mixed with carbon produces steel mixed metal.
When iron, carbon, chromium and nickel mix together, then they form stainless steel. These mixed alloys are strong, tough and does not get rust. This form of metals are used in many ways.
Components: Iron, carbon
Uses: Bridge, railway line, instrument, tank, ships
Components: Iron, Chromium, Nickel
Uses: Utensils, medical instruments
Components: Copper, tin
Uses: Coins, idols, ornaments, utensils, metals
1. Fill in the blanks:
- Aluminum is found as _____ ore.
- ____ metal can be cut easily from knife.
- Limestone is found in _____ and _____ states.
2. Write the names of any three maximum reactive metals?
3. What is ductility?
1. (i) bauxite (ii) Sodium, magnesium (iii) MP, Rajasthan
2. Sodium, Potassium, Aluminum, Copper, Iron
3. Making wires from metals is called ductility.