This section deals with metals and non metals. At the end, you will also get to solve some important MCQs.
Also Check: MCQs on electricity and magnetism
Metals and Non Metals | Properties of Metals and Non Metals
All the materials around us can be broadly classified into two categories, viz metals and non metals.
What are metals?
The materials that have the following physical properties are known as metals:
- Good conductors of heat and electricity: The metals allow the heat and electric current to pass through them.
- Malleability: The metals show malleability which means that they can be drawn into thin sheets. The materials having malleability are known as malleable.
- Ductility: The metals also show ductility which means that they can be drawn into thin wires. The materials having ductility are known as ductile.
- Lustrous nature: Metals are also lustrous which means that they have shiny surfaces. The reason behind the shiny surface in metals is that they give out electrons readily.
- Sonorous nature: The metals are also sonorous which means they produce sound when hit. It is due to this reason that the school bell is made up of a metallic material and not of non metallic materials.
- Hard: Metals are also hard. Owing to this hardness, they can change their shape easily but wont break down.
- High melting and boiling points: Metals in general have very high melting and boiling points.
The metals are hard, ductile, malleable and have very high melting and boiling points, as the positive ions present in them can slide past each other while still remaining together. So, instead of breaking apart, they change shape, resulting in increased toughness.
Examples of metals are Copper, Iron etc.
These were some physical properties of metals. Lets now discuss the chemical properties of metals below.
Chemical properties of metals
The metals have the following chemical properties:
1. Reaction of metals with oxygen.
Metals react with oxygen to form metallic oxides. The famous example of this is the rusting of iron, in which iron reacts with oxygen to form iron oxide (aslo called ferric oxide) known famously as rust. This reaction is shown below:
4Fe+ 3O2 → 2Fe2O3
The metallic oxides formed are basic in nature, and its solution will turn red litmus blue.
2. Reaction of metals with water
Metals react with water to form metal hydroxides.
Sodium metal reacts with water vigrously wlong with the liberation of heat. It is owing to this reason that sodium metal is always stored in kerosene (to avoid getting it in contact with the water).
3. Reaction of metals with acids
The metals also react with acid and produce hydrogen gas that burns with a ‘pop’ sound. But, not all metals react with all acids in all conditions.
The reaction of metals with acids can be represented as:
Metal + acid → salt + hydrogen gas
An example of this is the reaction between Magnesium and Hydrochloric acid,as shown below:
Mg + 2HCl → MgCl2 + H2
4. Reaction of metals with bases
Metals react with sodium hydroxide to produce salt and hydrogen gas. For example, Alumunium reacts with Sodium Hydroxide to produce Sodium Aluminate and Hydrogen, as shown below:
Al + NaOH → NaAlO2 + H2
5. Displacement reaction in metals
Metal displaces another metal from its compound in aqueous solution. For example: zinc (Zn) replaces copper (Cu)
from copper sulphate (CuSO4) solution (blue in colour). That is why, when zinc reacts with copper sulphate solution, the blue colour of copper sulphate solution disappears and a powdery red mass of copper is deposited at the bottom of the beaker.
The reaction can be represented as follows:
Copper Sulphate (CuSO4)(Blue)+ Zinc (Zn) → Zinc Sulphate (ZnSO4) (Colourless) + Copper (Cu) (Red)
To understand, which metal with replace which metal, we need to consider the reactivity series given below:
In a displacement reaction involving two metals, the metals lying above in the series will displace the metal lying below them in the displacement reaction.
What are non metals?
The materials that are soft and dull in appearance, non sonorous and poor conductors of heat and electricity are known as non metals. Examples of non metals are coal and sulphur.
Chemical properties of non metals
The non metals, in general show following chemical properties:
1. Reaction of non metals with oxygen
The non metals react with oxygen to form non-metallic oxides in general.
If sulphur is burnt (brning means reaction with oxygen), it form sulphur dioxide as shown below:
S + O2 → SO2
The non metal oxides are acidic in nature and therefore their solution turn blue litmus red.
2. Reaction of non metals with water
Generally, non-metals do not react with water though they may be very reactive in air. Such non-metals are
stored in water. Example : phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.