In this article, we will discuss the Non-Metals and Metalloids. One-liner type question usually comes from this topic.
- Non-metal may be solid, liquid or gas.
- Bromine is the only liquid non-metal.
- Non-metals are the elements that do not have the properties of the metals.
- They are the soft, non-lustrous, brittle, non-sonorous and poor conductor of heat and electricity .e.g. carbon, hydrogen, helium, neon krypton, etc.
- Carbon belongs to group 14 of the periodic table.
- Carbon occurs both in a free state as well as in the 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 the making of jewellery and cutting glass.
- Graphite is an exception. It is a good conductor of heat and electricity.
- Used in the nuclear reactor as a moderator.
Compounds of Carbon:
- It is colourless, odourless, neutral and highly poisonous gas in nature.
- Combines with hemoglobin to form Carboxyhaemoglobin, which is not able to absorb oxygen, as a result, leads to suffocation
- Woodfire 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.
- Occur in the air to the extent of 0.03-0.05 percent.
- Solid CO2 is known as dry ice.
- Dry ice is used in the transport of perishable food material as it provides the 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 the free state.
- This element which also exhibits the characteristic of allotropy.
- This is the second most abundant element in 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 exists most abundantly in the solid state in nature and used in the production of glass, cement, etc.
- Quartz is a crystalline form of SiO2.
- An 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 an inert atmosphere in different metallurgical operation.
- Used as a preservative in the food packing.
Compounds of Nitrogen:
- The 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 fertilizers and explosives.
- Nitrous oxide (N2O) is used as laughing gas.
- The symbiotic bacteria present in the root nodules of leguminous plant convert the atmospheric nitrogen into compounds of nitrogen .e.g. Azobactor.
- It is a highly reactive non-metal that is why it does not occur in the free state.
- Phosphorus is an essential constituent of bones, teeth, blood nerves and tissue.
- Bones contain 80% phosphorus.
Allotropes of phosphorus:
- White phosphorus:
- Red phosphorus
- Black phosphorus
- Scarlet phosphorus
- Violet phosphorus
- Oxygen exists in two allotropic forms that are in the most stable diatomic form(O2) and in a less stable triatomic form (O3) ozone.
- Oxygen is the supporter of combustion but it is non-inflammable.
- Oxygen dissolved in blood in the form of oxyhemoglobin.
- Liquid oxygen mixed with freshly divided carbon is used in place of dynamite in coal mining.
- 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 the position of the double bond in unsaturated organic compounds.
- Sulphur occurs in the free state in volcanic areas.
- Sulphur exists in five allotropic forms.
- Sulphur is used in the rubber industry for vulcanization of rubber.
- Sulphuric acid is also known as oil of vitriol or king of chemicals.
- Sulphuric acid is prepared by two processes i.e. lead chamber process and contact process.
- Halogens are highly reactive elements and therefore they do not exist in the free state but exist only in combined form.
- Halogens have the highest electron affinity so they act as strong oxidising agent.
- Their oxidising power decreases from fluorine to iodine.
- Chlorine is always present in the 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 a bleaching agent.
- Reacts with water to form HCl and HCIO.
- Used as a disinfectant and oxidizing agent.
- It is used as an antiseptic as tincture of Iodine.
- Used in the cure of Goitre.
- Turns starch solution blue.
- Helium, neon, argon, krypton, xenon, and radon are known as inert gases or noble gases.
- These elements have completely filled valence shell and so these do not form chemical bonds.
- These are always found in the free state but radon is not present in nature.
- In the atmosphere, argon is the most abundant noble gas but in the universe, helium is the most abundant gas.
- The mixture of Helium and Oxygen is used for artificial breathing of Asthma patients and by sea drivers.
- Helium is used as a pressuring agent in rockets to expel liquid oxygen and liquid hydrogen.
- Neon is used in a neon discharge lamp and signs for advertising purposes.
- Xenon is also known as stranger gas and a combined mixture of xenon and krypton is used in high-intensity photographic flash tubes.
- Radon is used in the preparation of an ointment for the treatment of cancer.
- A mixture of argon and nitrogen is used in an 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 tellurium.
- Typical metalloids have a metallic appearance but they are the 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