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Important Notes on Non-Metals and Metalloids

In this article we will discuss about the Non-Metals and Metalloids. One liner type question

usually comes from this topic. Every year there is a question from this topic in SSC Exam.

Non Metals:

-Non-metal may be solid, liquid or gas.

-Bromine is the only liquid non metals.

-Non metals are the elements that do not have the properties of the metals.

-They are soft, non lustrous, brittle ,non sonorous and poor conductor of heat and

electricity .e.g. carbon, hydrogen, helium, neon krypton etc.

Important Non metals


-Carbon belongs to the group 14 of the periodic table.

-Carbon occurs both in free state as well as in combined state.

-Carbon has two crystalline allotropes diamond and graphite.

Allotropes of Carbon:


-Diamond is the hardest substance and is the bad conductor of electricity.

-Diamond is the purest form of the Carbon

-Used in making of jewellery and cutting glass.


-Its an exception , it is a good conductor of heat and electricity.

-Used in nuclear reactor as a moderator.

Compounds of Carbon:

Carbon monoxide:

-It is colourless, odourless, neutral and highly poisonous gas in nature.

-Combines with haemoglobin to form Carboxyhaemoglobin, which is not able to

absorb oxygen as result leads to suffocation

-Wood fire or coal fire in a closed room leads to the formation of the carbon monoxide

which leads to the death of the persons in the rooms.

Carbon Dioxide:

-Occur in the air to the extent of 0.03-0.05 percent.

-Solid CO2 is known as dry ice.

-Dry ice is used is used in transport of perishable food material as it provides cold and

inert atmosphere which helps in killing bacteria, fungi, modules etc.

-Carbon dioxide is used by the plants in the process of photosynthesis for the

formation of oxygen.

-Carbides are the compound of carbon with metals or electro-negative elements.


-Silicon occurs in nature in the form of sand but never found in free state.

-This is a non-metallic element which also exhibits the characteristic of allotropy.

-This is the second most abundant element on the earth crust after oxygen

-Used as a superconductor in making computer chips.

-Silicon carbide is an artificial diamond called carborendum.

-Silica is also called sand which exist most abundantly in solid state in the nature and

used in the production of glass, cement etc.

-Quartz is a crystalline form of SiO .

Nitrogen(N ) :

-Important constituent of air about 79% by volume.

-Used in the manufacturing of nitric acid, ammonia and other nitrogen compounds.

-As a refrigerant in liquid form.

-To provide inert atmosphere in different metallurgical operation.

-Used as preservative in the food packing.

Compounds of Nitrogen:


-Most important compound of nitrogen.

-Prepared by Haber’s process.

-It is soluble in water and its aqueous solution is alkaline in nature.

-Used in refrigerator and manufacturing of fertilisers and explosives.

  1. Nitrous oxide(N O) is used as laughing gas .
  2. The symbiotic bacteria present in the root nodules of leguminous plant convert the

atmospheric nitrogen into compounds of nitrogen .e.g. Azobactor.


-It is highly reactive non metal that why it does not occursinfree state.

-Phosphorus is an essential constituents of bones, teeth, blood nerves and tissue.

-Bones contains 80% phosphorus.

Allotropes of phosphorus:

-White phosphorus:

-Red phosphorus

-Black phosphorus

-Scarlet phosphorus

-Violet phosphorus


-Oxygen exist in two allotropic form that is in most stable diatomic form(O ) and in less

stable triatomic form (O ) ozone.

-Oxygen is the supporter of combustion but it is non-inflammable.

-Oxygen dissolved in blood in the form of oxyhaemoglobin.

-Liquid oxygen mixed with freshly divided carbon is used in place of dynamite in coal


-Ozone is formed by the action of UV rays from the Sun on Oxygen and protects the

living beings by not allowing UV rays to reach the earth.

-Ozone is also used as germicide and disinfectant for sterilizing water and for

detecting position of double bond in unsaturated organic compounds.


-Sulphur occurs in free state in volcanic areas.

-Suphur exists in five allotropic form.

-Sulphur is used in rubber industry for vulcanization of rubber.

-Sulphuric acid is also known as oil of vitrol or king of chemicals.

-Sulphuric acid is prepared by two process i.e. lead chamber process and contact



-Halogens are highly reactive elements and therefore they do not exist in free state but

exist only in combined form.

-Halogens have highest electron affinity so they act as strong oxidising agent.

-Their oxidising power decreases from fluorine to iodine.

Chlorine(Cl ):

-Chlorine always present in combined state in nature in the form of chlorides .

-Chlorine was first discovered by Scheele by the action of hydrogen chloride on

manganese dioxide.

-Chlorine is used as an bleaching agent.

-Reacts with water to form HCL and HCIO.

-Used as disinfectant and oxidising agent ,


-It is used as an antiseptic as tincture of Iodine.

-Used in the cure of Goitre.

Turns starch solution blue.

Noble Gases:

-Helium, neon , argon, krypton , xenon and radon are known as inert gases or noble


-These elements have completely filled valence shell and so these do not form

chemical bonds..

-These are always found in free state but radon is not present in nature.

In atmosphere argon is the most abundant noble gas but in universe helium is the

most abundant gas.

-Mixture of Helium and Oxygen is used for artificial breathing of Asthama patients and

by sea drivers.

-Helium is used as pressuring agent in rockets to expel liquid oxygen and liquid


-Neon is used in neon discharge lamp and signs for advertising purposes.

-Xenon is also known as stranger gas and combined mixture of xenon and krypton is

used in high intensity photographic flash tubes.

-Radon is used in the preparation of ointment for the treatment of cancer.

-A mixture of argon and nitrogen is used in electric bulb.

-Krypton is used in high efficiency miner’s cap lamps.


-They have properties of both metals and non-metals.

-Six commonly known metalloids are boron, silicon, germanium, arsenic, antimony and


-Typical metalloids have a metallic appearance but they are brittle and only fair

conductor of electricity.

-Metalloids and their compounds are used in the manufacturing of alloys , biological

agents, flames retarders, glasses, optical storage


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