Metals and Non Metals
2. Properties of Materials
Before reading metal and non metal we must understand what is element and what is compound.
Element - an element is a pure substance which cannot be broken down further. eg - Gold, silver, oxygen, carbon etc.
Compound - is a substance made of two or more element. e.g. - water, carbon dioxide etc.
Before classifying material as metal or non metal, first think it is an element or a compound. In this chapter you have to classify only element as metal or non metal. so when anyone ask you Tree is metal or non metal, so just think can this be broken down further - if yes (tree is made of carbon) then just say it is a compound. It is a non-metal.
Materials can be classified into two types -
- Metals and
- Non-Metals
It is the properties of the metal which help us to decide which one is metal and which one is non-mental. So important properties are -
- Lustre
- Malleability
- Ductility
- Sonority
- Hardness
- Conduction of Heat
- Conduction of Electricity.
Lets define the properties one by one -
Lustre - It is a shine of a material. If material shines that means it is a metal and if it is not shining then it is a non metal. for example - Gold, silver, aluminium etc are metal because it shines. But Coal, sulphur etc is dull so it is non metal.
Exception - Diamond and Iodine which is non metal but also shine.
Malleability - is the ability of the material to be beaten into thin sheets. All Metals are Malleable but non metals are brittle.
Ductility - The property of material that enables it to be drawn into thin wires. All metals are ductile and non-ductile.
Sonority - The property of metals by which they produce a ringing sound when struck against a hard surface is called sonority. Metals when dropped produce a sonority sound but Non-metal cannot.
Hardness - The hardness of a material is its ability to resist being scratched or compressed.
- Metals are Hard - e.g - Iron, copper etc. - Exception - Mercury, Sodium and Potassium are soft
- Non Metals are soft - e.g. - Sulphur, graphite etc - Exception - Diamond is the hardest element on the earth.
Conduction of Heat - The process by which heat are transferred from one part of material to another is called conduction of heat. Metals are good conductor of heat that why it is used as utensils. Non metals are bad conductor of heat.
Conduction of electricity - The process by which certain material allow electricity to pass through them is called conduction of electricity and the material are called conductor electricity.
Metals are good conductor of electricity
Non Metals are poor conductor of electricity. Exception - Graphite is a non-metal but good conductore of electricity