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Physical Properties of Metals and Non Metals

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What is a Metal?

A metal is an element that is malleable and ductile and conducts electricity. Some of the examples are- Iron, Copper, Aluminium, Zinc, Silver, etc.

Physical Properties of Metals

  • Metals are Malleable- It means that they can be beaten into thin sheets with a hammer without breaking. Ex- Gold, Silver, Aluminium, Copper, etc. All these metals can be beaten into thin sheets called foils. The silver foils are used for decorating sweets. Aluminium foils are used for packing food items like biscuits, chocolates, medicines, cigarettes, etc. Milk bottle caps and cooking utensils are also made of aluminium foils. Similarly, copper sheets are used for making utensils and other containers.
  • They are Ductile- It means that metals can be drawn into thin wires. But all the metals are not equally ductile. Some are more ductile than the others. Gold, Silver, Copper and Aluminium are among the best ductile metals. Just one gram of Gold can be drawn into a thin wire of about 2 kilometers long. Copper and Aluminium are used in electrical wiring. Iron wires are used for making wire gauzes. Magnesium wires are used in science experiments in the laboratory and Tungsten wires are used for making the filaments of electric bulbs.
  • They are Good Conductors of Heat- It means that metals allow heat to pass through them easily. Silver, Copper and Aluminium are among the best conductors of heat. The cooking utensils and water boilers are usually made of Copper and Aluminium metals because they are good conductors of heat. However, there are certain exceptions to this rule. Lead and Mercury metals are poor conductors of Heat.
  • They are Good Conductors of Electricity- It means that metals allow electric current to pass through them. They offer very little resistance to the flow of electric current and hence show high electrical conductivity. Silver, Copper, Gold, Aluminium and Tungsten are good conductors of electricity. Therefore, electric wires are generally made of copper and aluminium metals. Exceptions to this rule include Iron and Mercury which are poor conductors of electricity.
  • They are Lustrous- It means that they have a shiny surface and can be polished. This property makes them useful in making jewellery and decoration pieces. Gold and Silver are used for making jewellery because they are shiny and bright. The shiny appearance of metals makes them good reflectors of light. Silver is an excellent reflector of light which makes it useful for making mirrors.
  • Metals are Hard- Metals are usually hard but the hardness varies from metal to metal. Iron, Copper, Aluminium, etc, are very hard and cannot be cut with a knife. But Sodium and Potassium are exceptions to this. They are soft metals which can be easily cut with a knife.
  • They are Strong- They have high tensile strength. It means that metals can hold large weights without breaking. For Example- Iron is very strong having a high tensile strength. Due to this reason, it is used in the construction of bridges, buildings, railway lines, girders, machines, vehicles and chains, etc. Exceptions include Sodium and Potassium.
  • Metals are Solids at Room Temperature- Most of the metals are like Iron, Copper, Aluminium, Silver, Golde, etc, are solids at the room temperature. Only one metal, Mercury, is in liquid state at the room temperature.
  • They Have High Melting and Boiling Points- It means that metals melt and vaporise at high temperatures. For example- Iron has a high melting point of 1535°C. This means that solid iron melts and turns into molten iron on heating at a high temperature of 1535°C. Similarly, Copper also has a high melting point of 1083°C. But there are some exceptions. Sodium, Potassium, Gallium and Cesium have low melting and boiling points.
  • Metals Have High Densities- It means that they are heavy substances. The density of Iron is 7.8 g/cm3 which is quite high. Exceptions include Sodium and Potassium having low densities of 0.97 g/cm3 and 0.86 g/cm3 respectively.
  • They are Sonorous- It means that they make a ringing sound when hit with an object. It is due to this property of metals that they are used for making bells, plate type musical instruments like cymbals and strings for stringed musical instruments like sitar and violin.
  • Metals Usually have a Silver or Grey Colour- Most metals have silver or grey colour. Exceptions include Copper and Gold. Copper has a reddish-brown colour whereas gold has a yellow colour.

Exceptions in Physical Properties of Metals

PropertyException

Heat Conductivity

Lead, Mercury (poor conductor)

Electrical Conductivity

Iron, Mercury (poor conductor)

Hardness

Sodium, Potassium, Lithium (soft)

High Tensile Strength

Sodium, Potassium (low)

Physical State

Mercury (Liquid)

High Melting and Boiling Point

Sodium, Potassium, Cesium,Gallium (low)

High Density

Sodium, Potassium, Lithium (low)

What is a Non-Metal?

A Non-Metal is an element that is neither malleable nor ductile and does not conduct electricity. Examples- Carbon, Sulphur, Phosphorus, Hydrogen, Oxygen, Chlorine, Bromine, Iodine, Helium, Neon, Diamond, Graphite.

Diamond

Diamond

Physical Properties of Non-Metals

  • Non-metals are Brittle- It means that non-metals are not malleable i.e. they cannot be beaten into thin sheets with a hammer. They break into small pieces when hammered. Ex- When Sulphur and Phosphorus are beaten with a hammer, they break into small pieces.
  • They are not Ductile- It means that they cannot be drawn into wires. They are easily snapped while stretching. For example- When Sulphur and Phosphorus are stretched, they break into pieces and do not form wires. Thus, we cannot get wires from non-metals.
  • They are Bad Conductors of Heat and Electricity- It means that they do not allow heat and electricity to pass through them. They do not conduct heat and electricity because they have no free electrons. Example- Sulphur, Phosphorus, etc. However, there are certain exceptions. Diamond is a non-metal which is a good conductor of heat and Graphite is a good conductor of electricity. Due to this property, Graphite is used for making electrodes.
  • They are Dull in Appearance- Non-metals are not lustrous. They have a dull appearance. Example- Sulphur, Phosphorus. Exceptions include Iodine which has a lustrous appearance.
  • They are Soft- Most of the Non-metals are soft. They can be easily cut with a knife. Example- Sulphur, Phosphorus. Exception include Diamond which is extremely hard.
  • Non-Metals are not Strong- They have low tensile strength. They cannot hold large weights. Example- Graphite, which is not strong and has a low tensile strength. When a large weight is placed on a graphite sheet, it breaks.
  • Non-Metals may be Solid, Liquid or Gases at the Room Temperature- They can exist in all the three physical states-solid, liquid and gaseous. Carbon, Sulphur and Phosphorus are solid; Bromine is liquid and Hydrogen, Oxygen, Nitrogen, Chlorine are gaseous non-metals.
  • They have Low Melting and Boiling Points- It means that they melt and vaporise at comparatively low temperatures. Example- Sulphur has a low melting point of 119°C. Exceptions include Diamond and Graphite having melting point of more than 3500°C which is quite high.
  • Non-metals Have Low Density- It means that they are light substances. The density of Sulphur is 2 g/cm3. Exception include Iodine which has high density.
  • They are not Sonorous- They do not make a sound when hit with an object.
  • They have Different Colours- Sulphur is yellow, Graphite is black, Chlorine is yellowish-green whereas Hydrogen and Oxygen are colourless.

Exceptions in Physical Properties of Non-Metals

PropertyException

Heat Conductivity

Diamond (good conductor)

Electrical Conductivity

Graphite (good conductor)

Lustre

Iodine (shiny)

Softness

Diamond (hard)

Low Melting and Boiling Point

Diamond, Graphite (high)

Low Density

Iodine (high)

Iodine crystals showing a metallic lustre

Iodine crystals showing a metallic lustre

Comparison of Metals and Non-Metals

MetalsNon-Metals

Malleable and Ductile

Brittle

Good conductors of heat and electricity

Bad conductors of heat and electricity

Lustrous

Non-lustrous

Solid at room temperature

Soild, liquid or Gas

High tensile strength

Low tensile strength

Sonorous

Not sonorous

Hard

Soft

High density

Low density

High melting and boiling point

Low melting and boiling point

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