What is Non-Metal?
Non-metals are the elements which form negative ions by accepting or gaining electrons. Non-metals usually have 4, 5, 6 or 7 electrons in their outermost shell.
Non-metals are those which lack all the metallic attributes. They are good insulators of heat and electricity. They are mostly gases and sometimes liquid. Some of then are even solid at room temperature like Carbon, sulphur and phosphorus.
Properties of Non metals
Characteristic properties of non-metals are high ionization energies and high electronegativity. Owing to these properties, non-metals usually gain electrons when react with other compounds, forming covalent bonds.
The following are the general properties of non-metals.
- The atoms of non-metals tend to be smaller than those of metals. Several of the other properties of non-metals result from their atomic sizes.
- Non-metals have high electronegativities. This means that the atoms of non-metals have a strong tendency to attract more electrons than what they would normally have.
- Non-metals have high electronegativities. This means that the atoms of non-metals have a strong tendency to hold on to the electrons that already have. In contrast, metals rather easily give up one or more electrons to non-metals, metal therefore easily form positively charged ions, and metals readily conduct electricity.
Physical Properties of Non-Metals
- Under normal conditions of temperature and pressure, some non-metals are found as gases, some found as solids and one is found as liquid. In contrast, except mercury, all metals are solids at room temperature. The fact that so many non-metals exist as liquids or gases means that non-metals generally have relatively low melting and boiling points under normal atmospheric conditions.
- In their solid-state, non-metals tend to be brittle. Therefore, they lack the malleability and ductility exhibited by metals.
- Ductility is the property of the material to be stretched into wires but non-metals are not ductile except for carbon, as carbon fibres find uses in a wide variety of industries including sports and music equipment.
- Another property characteristic to metals is absent in non-metals called malleability. They can’t be drawn into sheets as they are brittle and break on applying pressure.
- Non-metals exhibit very low electrical conductivities. The low or non-existent electrical conductivity is the most important property that distinguishes non-metals from metals.
- They are not sonorous and do not produce a deep ringing sound when they are hit with another material. They are also bad conductors of heat and electricity except for graphite.
List of Non-Metals (the Complete List)
Chemical Properties of Non-Metals
1. Reaction with Water
A non-metal does not react with water but it is usually very reactive in air, which is why some of them are stored in water. For example, one of the highly reactive non-metals is phosphorus and it catches fire when exposed to air that is why it is stored in water to prevent its contact with atmospheric oxygen.
2. Reaction with Acids
None of the non-metals is known to react with acids.
3. Reaction with Bases
The reaction between non-metals and bases is a very complex one. The reaction of chlorine with bases like sodium hydroxide gives products like sodium hypochlorite, sodium chloride as well as water.
4. Reaction with Oxygen
Oxides of non-metals are formed when it reacts with oxygen. The oxides of non-metals are acidic or neutral in nature.
When sulphur reacts with oxygen, we get sulphur dioxide.
S + O2 → SO2
When sulphur dioxide reacts with water it forms sulphurous acid.
SO2 + H2O → H2SO3
5. Reaction with metal
Non-Metals react with metal, generally forming Ionic compounds.
Na+ + Cl– → NaCl
Uses of Non-Metals
- For the preparation of ammonia, nitric acid and fertilizers, nitrogen is used.
- For the purification of water, chlorine is used.
- Hydrogen is very useful as rocket fuel.
- Carbon can be used to make pencils when it is in the graphite form.
- Sulphuric acid is prepared using sulphur.
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