Properties of Non-metals
The element which has the tendency to take negative electrons by accepting electrons is called non-metal. That is, electricity is negative in non-metal. Such as carbon, nitrogen, sulfur, etc. Non-metals are found in all three states: solid, liquid, and gas. The nonmetals are divided into two categories reflecting their relative propensity to form chemical compounds: reactive nonmetals and noble gases. The reactive nonmetals vary in their nonmetallic character. The noble gases are distinguished by their great reluctance to form compounds with other elements.
Physical properties of non-metals
The main physical properties of non-metals are as follows-
1. Metallic luster
Non-metals do not have any special luster like metals, their surface is dirty. Only iodine and graphite are shiny non-metals.
2. Electrical and Thermal Conductivity
Nonmetals are not conductors of electricity and heat because free electrons are not found in them. While metals are conductors of electricity and heat. The exception is the conduction of electricity due to the presence of free electrons in the graphite, which is an allotrope of carbon.
3. Brittleness
Non-metals are brittle, meaning they are broken into small pieces by beating them with a hammer. While the metal is converted into a sheet upon beating with a hammer.
4. Tensile
Tensile properties are not found in non-metals, that is, they cannot be pulled and converted into the wire. While wires can be made by pulling metals.
5. Hardness
Although solid fluids and gases are found in all three phases in nonmetals, solid non-metals are also less hardy than the expected metals. As an exception, diamond is the most rigid form of carbon.
6. Melting and Boiling Point
Non-metals have lower melting and boiling points than metals. Exceptionally, carbon, boron, and silicon have higher melting points and boiling points.
7. Density
The densities of non-metals are lower than those of metals. As an exception, the density of diamond and iodine is higher than that of many metals.
8. Sound
No sound similar to that of metals is produced when beating non-metals.
9. Solubility
Non-metals dissolve in many fluid solutions.
10. Physical State
Most of the non-metals exist in two of the three states of matter at room temperature: gases (oxygen) and solids (carbon). Only bromine exists as a liquid at room temperature.
Chemical properties of non-metals
The major chemical properties of non-metals are as follows –
1. Reaction with Oxygen
Non-metals combine with oxygen to form acidic or neutral oxides.
C + O2 → CO2
(Carbon + oxygen → Carbon Dioxide – acidic)
S + O2 → SO2
(Sulphur + Oxygen → Sulphur Dioxide- acidic)
2. Reaction with Hydrogen
Non-metal reacts with hydrogen to form hydride by covalent bonds.
H2 + S → H2S
(Hydrogen + sulfur → Hydrogen sulfide)
N2 + 3H2 → 2NH3
(Nitrogen + Hydrogen → Ammonia)
3. Action with chlorine
Non-metals react with chlorine to form chloride. Its nature is covalent.
H2 + Cl2 → 2HCl
(Hydrogen + Chlorine → Hydrogen chloride)
P4 + 6Cl2 → 4PCl3
(Phosphorous + Chlorine → Phosphorous trichloride)
4. Displacement Reaction
Not only metals but also non-metals can take part in displacement reactions depending upon their order of reactivity. The more reactive non-metals replace the less reactive non-metals with their salt solution. For example, chlorine can displace bromine from the non-metal salt solution.
Cl2 + 2NaBr → 2NaCl + Br2
5. Reaction with acids
Normally non-metals do not react with dilute acid because non-metals themselves being acceptors of electrons would not donate electrons to acids and so would not react with dilute acids. However, some hot concentrated acids like sulphuric and nitric acids can oxidize nonmetals like sulfur, carbon, phosphorus, etc. Their reaction is possible only when the electrons are replenished by the protons formed in the reaction.
S + 4HNO3(highly conc..) → SO2 + 4NO2 + 2H2O
6. Electrical decomposition
Generally, metals are collected at the cathode and non-metals at the anode due to the electrolysis of salts.
