Non metals and their compounds
Carbon occurs naturally as diamond and graphite. It also occurs in an impure form as coal and in the combined state as carbon IV oxide, natural gas, petroleum and wood. Carbon exists in network crystals with the atoms of the crystals held together by covalent bonds. It exhibits an oxidation number of +2 and +4 in its compound..
Allotropes of carbon
Allotropy is the existence in the same physical state, of two or more structural forms of the same element. Carbon can exist in three different allotropic forms. These are, diamond, graphite and amorphous or non-crystalline. Diamond and graphite form the crystalline carbon.
Diamond: it is the purest form of naturally occurring carbon. It is found as colourless, lustreless solids which can be transformed into brilliant gems. Diamond crystal is octahedral in shape.
*Structure of the diamond crystal
Note: artificial diamonds are made by subjecting graphite to very high pressure and temperature for several hours in the presence of a catalyst such as rhodium or nickel.
Properties of diamond
1. It is very dense and resistant to high temperature and chemical attack.
2. It is the hardest known substance.
3. It is a non-conductor of heat and electricity, because it has no free valence electrons.
4. It has a high melting point.
Uses of diamond
1. It is used in the manufacture of glass cutters and rock breakers.
2. Its high refractive index makes it valuable as jewellery.
3. Being very dense and hard, diamond is used as abrasives to sharpen very hard tools.
4. Diamond is also used as pivot support in precision instruments.
Graphite exists as black, slippery, hexagonal crystals. The carbon atoms in graphite, form flat layers, and are joined together by strong covalent bonds.
* the structure of the graphite crystal
The Acheson process involves the industrial heating of coke to a high temperature, in an electric furnace.
Properties of graphite
1. Graphite is an opaque, flaky, soft crystalline solid with metallic lustre.
2. Unlike diamond, graphite is a good conductor of heat and electricity because of the presence of mobile electrons in the crystal lattice.
3. The mobile electrons exist since only three out of the four valence electrons of each carbon atom in the graphite are involved in bond formation, while the fourth electron is delocalized and free to move within the structure.
4. It is chemically inert and has a high melting point, but less dense than diamond.
Uses of graphite
1. Graphite is used as a black pigment in paints and as a neutron moderator in atomic piles.
2. Graphite is used as a lubricant in engines, where high temperatures melt ordinary lubricant.
3. It is used to line crucibles used for making high-grade steel and in the coating of irons.
4. A mixture of graphite and clay is used in the manufacture of lead pencils.
5. As a good conductor of electricity, graphite is used as electrodes in electrolytes.
Properties of diamond and graphite
|1. Colourless, transparent solid with high refractive index.||Black, opaque solid with a Metallic lustre.|
|2. Density is 3.5gcm-3||Average density is 2.3gcm-3|
|3. Hardest known natural substance.||Very soft, marks paper|
|4. Non-conductor of electricity||Good conductor of electricity|
|5. Very inert, but burns in air at about 900°C to form carbon IV oxide.||More reactive than diamond; burns in air at about 700°C to form carbon IV oxide; attacked by oxidizing agents such as potassium trioxochlorate V acid to form the oxides.|
|6. Octahedral in shape||Hexagonal in shape|
Amorphous carbons are not considered as true allotropes of carbon, because the carbon atom consists of minute crystals of graphite bound together by impurities. The other amorphous carbon includes the following; wood charcoal, animal charcoal, sugar charcoal, carbonblack, lamp black or soot.
Coal is a black organic rock formed from the vegetation of the Carboniferous period. It is a very impure carbon, containing minerals and modified remains of substances present in the ancient trees and other plant life.
Types of coal
There are four types of coal, namely: peat, lignite (brown coal), bituminous (soft coal) and Anthracite (hard coal) which is about 96% pure carbon.
Destructive distillation of coal
Coal > coke + ammoniacal liquor + coal tar + coal gas. This process is known as destructive distillation of coal.
*Industrial manufacture of coal gas by the destructive distillation of coal
Terms in destructive distillation of coal
Coke: coke is the non-volatile residue left behind after the destructive distillation of coal. It is also used in the manufacture of gaseous fuel and as a reducing agent in the extraction of metals from their ores.
Ammoniacal liquor: ammoniacal liquor is a solution of ammonia in water. It is used in the preparation of ammonium tetraoxosulphate VI, which is used in fertilizer.
Coal tar: coal tar is a thick, black liquid. It is a mixture of many organic substances which can be separated by fractional distillation, among which are benzene, toluene, phenol and Naphthalene.
Coal gas: coal gas is an important gaseous fuel, because it is a cleaner and more efficient fuel than coal or other solid fuels.
Gasification of coke (fuel gases)
Producer gas: it has a low heating power because it contains about 70% non combustible nitrogen and 30% carbon II oxide. Produce gas is not expensive and is widely used to heat furnace retorts during manufacture of zinc and coal gas.
Water gas: water gas is a more efficient fuel than producer gas because, in the water gas, both hydrogen and carbon II oxide burn in air, releasing a lot of heat.
*Production of producer gas and water gas
Properties of carbon
2. Reaction in a charcoal pot
*Combustion in a charcoal pot
3. Combination reactions
4. As reducing agents
5. Reaction with strong oxidizing agents
Oxides of carbon
When two carbon is heated in oxygen or air, it forms two oxides, namely carbon IV oxide, (CO2), and carbon II oxide, (CO). The oxides formed depends on the availability of oxygen.
Carbon IV oxide: carbon IV oxide was first observed by Van Helmont towards the end of the sixteenth century. It is one of the naturally occurring inorganic compounds of carbon. However, it is very important to green plants which make use of it, in the presence of water and sunlight, to produce starch. This process is known as photosynthesis.
*Laboratory preparation of carbon IV oxide
Uses of carbon (IV) oxides
1. It is used in fire extinguishers because it does not support combustion and it is a heavy gas.
2. Carbon IV oxide is used as a coolant in nuclear reactors.
3. It is used in the solvay process to manufacture sodium hydrogen trioxocarbonate IV and sodium trioxocarbonate IV.
4. Solid carbon IV oxide (dry ice) is used as cooling agents in refrigerators for keeping substances cold.
5. Solution of carbon IV oxide in water has a pleasant taste, hence, it is used in manufacture of mineral water, such as coca cola, Sprite, lemonade etc.
6. It is used as a leavening agent in the baking of bread.
7. Green plants use it during the process of photosynthesis.
Carbon II oxide
Carbon II oxide is a poisonous, colourless and odourless gas. It is present in coal gas and other gaseous fuels.
*Laboratory preparation of carbon II oxide
Uses of carbon II oxide
1. It is used as a reducing agent in the extraction of metals from their ores.
2. It is used in the commercial production of methanol by catalytic process.
3. It is an important constituent of gaseous fuels like producer gas and water gas, thus it is used as a fuel.
Oxygen is the first element in group VI of the periodic table was discovered by Scheele in 1772 and Priestley in 1774. It is a diatomic molecule and the most abundant element on Earth. Water, one of the most abundant compounds on Earth, is made up of 88% oxygen by mass.
*Preparation of oxygen
Physical properties of oxygen
1. It is neutral to litmus paper.
2. Its density is about the same as that of air.
3. Pure oxygen is a colourless, odourless and tasteless gas.
4. Gaseous oxygen liquefies at -183°C and solidifies at -225°C.
5. It is slightly soluble in water.
Chemical properties of oxygen
1. Oxygen gas supports combustion of many substances.
2. When sodium and potassium are heated in a plentiful supply of oxygen, higher oxides (Na2O2 and K2O2) are formed instead of the basic oxide.
3. Non-metals like sulphur, carbon and phosphorus burn in oxygen to form acidic oxides.
4. The oxygen we breathe in oxidizes the carbohydrate we eat to release energy.
5. Most hydrocarbons burn in oxygen to form carbon IV oxide and water.
Uses of oxygen
1. Oxygen is used in the manufacture of chemicals like tetraoxosulphate VI acid, trioxonitrate V acid and ethanoic acid.
2. Liquid oxygen and fuels are used as propellants for space rockets.
3. It is used in the steel industry for the removal of carbon, sulphur and phosphorus, i.e in the L-D process for making steel.
4. Oxygen is used in oxy-ethyne and oxy-hydrogen flames for cutting and welding metals.
5. It is used in resuscitating fainting patients.
6. Oxygen is used to support breathing in high altitude flights, mountaineering and diving operations.
Hydrogen is the lightest of all elements making up about 1% of the earth crust. Hydrogen is widely distributed in combination with other elements in the form of water, acids, organic substances and petroleum products.
*Preparing of water
Physical properties of hydrogen
1. Pure hydrogen is a colourless, odourless and tasteless gas.
2. It is relatively insoluble in water.
3. It is the lightest known substance, about 14.4 times less dense than air.
4.it is neutral to litmus paper.
5. It has a very low boiling point of -253°C.
Chemical properties of hydrogen
1. Hydrogen combines directly with the more reactive metals to form ionic hydride.
2. Pure hydrogen burns with a pale blue flame as it combines with oxygen to produce steam.
3. Hydrogen combines directly with the halogens to produce halides.
4. Hydrogen combines directly with nitrogen to produce ammonia.
5. Hydrogen reacts with oxides of copper, lead, iron, and zinc to produce a strong reducing agent.
Uses of hydrogen
1. It is used for filling balloons
2. It is used to inflate airships, but it is highly inflammable.
3. Hydrogen is used in the synthesis of ammonia.
4. Hydrogen is also used in atomic hydrogen flames.
5. Liquid hydrogen is used as a rocket fuel.
6. It is used in hardening vegetable and animal oil for the manufacture of margarine, soap and candles.
7. It is used in oxy-hydrogen flames to produce high temperatures (over 2000°C) that can melt metals.
Water is by far the most abundant substance in plant and animal tissues as well as the world around us. It accounts for about 70% of the human body and is higher in many growing plants.
Properties of water
1. It is neutral to litmus
2. Pure water is a clear, colourless, tasteless and odourless liquid.
3. It has a maximum Density of 1gcm-3 at 4°C.
4. It has a boiling point of 100°C and a freezing point of 0°C.
Chemical properties of water
1. Water reacts with metals to a degree varying with their position in the electrochemical series.
2. Non metals like carbon, chlorine and silicon also react with water.
3. Oxides of alkaline metals readily form strong alkalis or hydroxides with water.
4. Water reacts with organic and inorganic compounds.
Elements that make up a family of halogens are fluorine, chlorine, bromine, iodine and astatine. Fluorine is the most reactive element among the halogens, and is in many ways unique. Bromine and iodine are chemically very similar to chlorine. Astatine which is radioactive has been made artificially and does not occur naturally.
Hydrogen chloride is a hydride compound of chlorine which exists as a gas at s.t.p. Hydrogen chloride was first prepared by Priestley in 1772.
Physical properties of hydrogen chloride
1. Dry Hydrogen chloride dissolves readily in non-polar solvents.
2. It does not support combustion
3. It fumes strongly in moist air, forming droplets of hydrochloric acid.
4.it is very soluble in water, forming an aqueous solution of hydrochloric acid.
5. It turns blue litmus paper red.
6. It is slightly denser than air.
7. Pure Hydrogen chloride is a colourless gas with a sharp irritating smell.
Chemical properties of hydrogen chloride
1. It reacts with many metals on heating.
2. It reacts with ammonia gas to form a dense white fumes of solid ammonium chloride.
Nitrogen was discovered in 1772 by David Rutherford. It constitutes about 78% by volume of the atmosphere.
*Preparation of nitrogen from air
Physical properties of nitrogen
1. Nitrogen is a colourless, odourless and tasteless gas
2. Pure nitrogen is slightly less dense than air
3. It is slightly soluble in water
4. It has a melting point of -210°C and boiling point of -196°C.
5. It exhibits oxidation states varying from -3 to +5 in its various compounds.
Chemical properties of nitrogen
1. It combines with Hydrogen to produce ammonia
2. It combines with some metals at high temperature to form nitrides.
Sulphur makes up about 0.1% of the Earth’s crust. It is a yellow now Metallic solid element and the second member in group VI of the periodic table.
Physical properties of sulphur
1. Sulphur is a yellow solid
2. It is insoluble in water but soluble in carbon IV sulphide and methyl benzene
3. It exists in two forms- amorphous and crystalline.
4. It is a bad conductor of heat and electricity
5. It has a melting point of 119°C and a boiling point of 444°C.
6. It is a bad conductor of heat and electricity.
Chemical properties of sulphur
1. It combines directly with other elements
2. Sulphur readily oxidizes when warmed with concentrated tetra-oxosulphate VI acid to form sulphur IV oxide.
3. Sulphur reacts with hot concentrated alkaline solution to form a mixture of sulphides and trioxosulphate and trioxosulphate IV.
Noble gases constitute about 1% by volume of air and are characterised by their chemical inertness, and they consist of helium, neon, argon, Krypton, xenon and radon.
Uses of Noble gases
1. Helium, neon and argon are used in advertisement signs since they give out coloured light.
2. Argon is used in gas.
3. Radon, a radioactive, is used in medicine for treating cancer.
4. Neon lights are used in aerodromes beacons, as they penetrate fog.
5. A mixture of Krypton and xenon is used in the photographer’s flash tube for taking high speed pictures.
6. Helium being non-combustible and almost as light as Hydrogen is used in filling balloons.
1. A piece of burning Sulphur will continue to burn in a gas jar of oxygen to give Misty fumes which readily dissolve than water. The resulting liquid is? (Jamb 1983)
A. Sulphur IV trioxide
B. Tetraoxosulphate VI acid
C. Trioxosulphate IV acid
D. Dioxosulphate II acid
E. Hydrogen sulphide
2. Anhydride is an oxide of a non-metal.
A. Which will not dissolve in water
B. Whose solution in water has a pH greater than 7
C. Whose solution in water has a pH less than 17
D. Whose solution in water has a pH of 7
3. The most important use of hydrogen is in the? (Jamb 2002)
A. Manufacture of ammonia
B. Manufacture of methylalcohol
C. Manufacture of ethyl alcohol
D. Hydrogenation of oils
4. Some Noble gases will give out coloured lights under? (Jamb 2017)
A. High pressure
B. Low pressure
C. Low temperature
D. High temperature
5. The following are uses of sulphur except? (Wassce 1988)
A. Manufacture of tetraoxosulphate VI acid
B. Prevention of the growth of fungi
C. Vulcanization rubber
D. Manufacture of dyes
E. Coating of steel to prevent rusting
6. Which of the following gases are produced when dilute tetraoxosulphate VI acid reacts with a mixture of iron filings and iron II sulphide? (Wassce 1990)
A. Hydrogen and sulphur IV oxide
B. Hydrogen and hydrogen sulphide
C. Hydrogen sulphide and sulphur IV oxide
D. Sulphur IV oxide and sulphur VI oxide
E. Hydrogen sulphide and sulphur VI oxide.
7. The method of collection of gases prepared in the laboratory depends on their? (Wassce 2004)
A. Odour and atomicity
B. Colour and odour
C. Atomicity and density
D. Solubility and density
8. The crystal layers in graphite are held together by? (Wassce 2014)
A. Covalent bond
B. Electrostatic forces
C. Ionic bond
D. Van der Waals forces