Metals and Non-metals

Metals and Non-metals

Physical Properties of Metals and Non-metals

Conductivity

Ductility

Hardness

Lustre

Malleability

Physical State

Sonorous

Conductivity:

Metals (such as iron or copper) are good conductors of heat and electricity.

Non-metals (such as coal or sulphur) are poor conductors of heat and electricity. Graphite is an exception as it is a good conductor of electricity.

Ductility:

Metals (such as aluminium and copper) are ductile, which means that they can be drawn into wires.

Non-metals are brittle (break down when struck) and hence, they cannot be drawn into wires.

Hardness:

All metals are hard though there are some exceptions. Sodium and potassium are soft and can be cut with a knife.

Most non-metals are soft. Diamonds are exceptions as they are the hardest material found on Earth. However, they are also very brittle and break when struck with a hammer.

Lustre:

Metals (such as gold, silver and copper) are lustrous, which means that they reflect light from their surface and can be polished.

Non-metals (such as coal) are generally dull and do not reflect light. Hence, they lack metallic lustre

Malleability:

Metals (such as silver and aluminium) are malleable, which means that they can be beaten into thin sheets.

Since non-metals break easily, they cannot be pounded into sheets.

Physical State:

Most metals remain solid at room temperature, except mercury and gallium which remain liquid at room temperature.

Most non-metals exist in two of the three states of matter at room temperature: Gases (such as oxygen), and Solids (such as carbon).

Sonorous:

Metals produce ringing sounds when they are struck and hence, they are sonorous, except Mercury which is liquid in nature.

Non-metals are non-sonorous and do not produce the typical metallic sound when they are struck. 

Examples:

Metals:

Iron, copper, aluminium, calcium, magnesium, etc.

Non-Metals:

Sulphur, carbon, oxygen, phosphorus, etc.

Physical Properties of Metals:

Metals are:

=> hard to touch.

=> lustrous i.e., freshly Cut surfaces of metals have characteristic shining.

=> malleable; the property of metals by which they can be beaten mW thin sheets is called malleability.

=> ductile; the property of metal by which it can be drawn into wires is called ductility.

=> sonorous i.e., metals produce ringing sound when struck on a hard surface.

=> Good conductors of heat and electricity.

==> Metals like sodium and potassium are soft and can be cut with a knife.

==> Mercury is the only metal which is found in the liquid state at room temperature.

Physical Properties of Non-metals:

Non-metals are soft and dull (e.g., coal and sulphur).

Non-metals are generally brittle, i.e., they break down into a powdery mass on tapping with a hammer.

They are not sonorous.

They are poor conductors of heat and electricity.

Note:

 Copper Vessels also acquire a dull green coating (made up of copper hydroxide and copper carbonate) when they are exposed to moist air. It is called Verdigris.

Chemical Equation for Green Coating on Copper

Copper (Cu) + Moist Air (Water (H2O) + Oxygen (O2) + Carbon Dioxide (CO2)) → Copper Hydroxide (Cu(OH)2) + Copper Carbonate (CuCO3)

2Cu + H2O + CO2 + O2 → Cu (OH)2 + CuCO3

Copper carbonate and copper hydroxide are basic in nature.

Note: This green coating can be copper chloride if the copper reacts with sea air, or copper acetate if the copper reacts with acetic acid.

Chemical Properties of Metals and Non-metals

Reaction of Metals with Oxygen

Reaction of Metals with Water

Reaction of Metals with Solutions of Other Metal Salts

Reaction of Different Metals and Non-metals with Acids

Reaction of Metals with Oxygen

When metals react with oxygen, they form metal oxide.

Metal + O2 → Metal Oxide

For Example:

1. Copper + Oxygen → Copper Oxide (black)

2Cu + O2 → 2CuO

2. Aluminium + Oxygen → Aluminium Oxide

4Al + 3O2 → 2Al2O3

3. Magnesium + Oxygen → Magnesium Oxide

2Mg + O2 → 2MgO

The reactivity of metals with oxygen differs.

For Example:

=> Sodium and Potassium react so vigorously with air that they catch fire when they are kept in open. Hence, they are immersed in kerosene to store them.

=> The surfaces of Magnesium, Aluminium, Zinc and Lead are covered with a thin layer of oxide to make sure that they do not get oxidised anymore.

=> While iron does not burn when heated, iron filings burn vigorously.

=> Copper surface is coated with a thin layer of black copper oxide to prevent the process of further oxidation from taking place.

=> Gold and silver do not react with Oxygen.

Amphoteric Oxides:

 Some metal oxides react both with acids and bases to produce salts and water. Such metal oxides are called amphoteric oxides.

For example:

Aluminium Oxide + Hydrochloric Acid → Aluminium Chloride + Water

Al2O3 + 6HCl → 2AlCl3 + H2O

Aluminium Oxide + Sodium Hydroxide → Sodium Aluminate + Water

Al2O3 + 2NaOH → 2NaAlO2 + H2O

Reaction with Oxygen:

(a) For Metals:

Generally, when metals are reacted with oxygen they will form metallic oxides. And these metallic oxides are basic in nature.

Example-1: Rusting of Iron. Following is the reaction to express it.

Iron (Fe) + Oxygen (O2) + Water (H2O) → Iron Oxide (Fe2O3)

Testing of nature of Rusting:

(i) Collect a spoonful of rust and dissolve it in a very little amount of water.

(ii) The rust remains suspended in water. Shake the suspension well.

(iii) Test the solution with red and blue litmus papers. The red litmus turns blue.

So, generally metallic oxides are basic in nature.

(b) For Non-metals:

Generally, non-metals also produce oxides when reacted with oxygen. But, in contrast to metals, these oxides are acidic in nature.

Testing the nature of non metal:

(i) Take a small amount of powdered sulphur in a deflagrating spoon and then heat it.

(ii) As soon as sulphur starts burning, introduce the spoon into a gas jar/ glass tumbler.

(iii) Cover the tumbler with a lid to ensure that the gas produced does not escape.

(iv) After some time remove the spoon. Add a small quantity of water into the tumbler and quickly replace the lid. Shake the tumbler well. Check the solution with red and blue litmus papers.

(v) The name of the product formed in the reaction of sulphur and oxygen is sulphur dioxide gas. When sulphur dioxide is dissolved in water sulphurous acid is formed. Following is the reaction to express it:

Sulphur dioxide (SO2) + Water (H2O) → Sulphurous acid (H2SO3)

(vi) The sulphurous acid turns blue litmus paper red.

Generally, oxides of non-metals are acidic in nature.

Reaction of Metals with Water

Metal + (cold) Water → Metal hydroxide + Hydrogen

Metal + Stream → Metal oxide + Hydrogen

For Example:

Sodium + Water → Sodium Hydroxide + Hydrogen + Heat

2Na + 2H2O → 2NaOH + H2 + Heat

Calcium + Water → Calcium Hydroxide + Hydrogen

Ca + 2H2O → Ca(OH)2 + H2

Magnesium + Water → Magnesium Hydroxide + Hydrogen

Mg + 2H2O → Mg(OH)2 + H2

Aluminium + Water → Aluminium Oxide + Hydrogen

2Al + 3H2O → Al2O3 + 3H2

Iron + Water → Iron Oxide + Hydrogen

3Fe + 4H2O → Fe3O4 + H2

The reactivity of metals with water differs.

For Example:

=> Sodium, Potassium and Calcium react with cold water.

=> Magnesium reacts slowly with hot water to form slightly soluble magnesium hydroxide. Aluminium, Zinc and Iron react with steam.

=> Lead, Copper, Silver and Gold do not react with water.

Note: Calcium and magnesium float on water as bubbles of hydrogen stick to their surface.

Reaction of Metals with Solutions of Other Metal Salts:

Metal A + Salt Solution of Metal B → Salt Solution of Metal A + Metal B

More reactive metals replaces less reactive metals.

Less reactive metals cannot replace more reactive metals.

For Example:

Iron + Copper Sulphate → Iron Sulphate + Copper

Fe + CuSO4 → FeSO4 + Cu

The reactivity series

Note:

When metals react with acids, they produce hydrogen gas with produce a 'pop' sound when it burns.

Iron reacts with hydrochloric acid and sulphuric acid on heating.

Copper does not react with hydrochloric acid (even when it is heated) but reacts with sulphuric acid on heating.

Applications of Metals:

(i) Metals are generally used in making of machines, automobiles, airplanes, cars, satellites, etc.

(ii) Some metals are used in making wires like copper, etc.

(iii) Some metals are used for making ornaments like gold, silver, etc.

Applications of Non - Metals:

(i) The oxygen necessary for all living beings to survive is a non-metal.

(ii) Some non-metals are used as fertilizers to enhance the growth of plants.

(iii) Some non-metals are used for water-purification.

(iv) Some non-metals are used as antiseptic.

(v) Non-metals used in crackers.