Chapter 7_5: Acids, Bases and Salts:

Acids are sour in taste. Bases are bitter in taste and soapy to touch. „

Acid turns blue litmus red. Bases turn red litmus blue. „

Substances which are neither acidic nor basic are called neutral. „

Solutions of substances that show different colour in acidic, basic and neutral solutions are

called indicators. „

An acid and a base neutralise each other and form a salt. A salt may be acidic, basic or

neutral in nature.

The rain becomes acidic because carbon dioxide, sulphur dioxide and nitrogen dioxide (which are

released into the air as pollutants) dissolve in rain drops to form carbonic acid, sulphuric acid and

nitric acid respectively.

When the solution is basic, phenolphthalein gives a pink colour. On the other hand, when the

solution is acidic, it remains colourless

When an acidic solution is mixed with a basic solution, both the solutions neutralise the effect of

each other

When an acid solution and a base solution are mixed in suitable amounts, both the acidic nature of

the acid and the basic nature of the base are destroyed

In neutralisation reaction, heat is always produced, or evolved. The evolved heat raises the

temperature of the reaction mixture

The reaction between an acid and a base is known as neutralisation. Salt and water are produced in

this process with the evolution of heat

Organic matter releases acids which neutralises the basic nature of the soil.

Each cell in our body contains an acid, the deoxyribonucleic acid deoxyribonucleic acid or DNA

DNA. It controls every feature of the body such as our looks, colour of our eyes, our height etc.

Proteins that build part of our cells are also made of amino acids amino acids. The fats in our body

contain fatty acid.

Chapter 10_2: Acids, Bases and Salts

A substance is acidic or basic by change in colour. There are some substances whose odour changes

in acidic or basic media. These are called olfactory indicators.

The reaction of a metal with an acid can be summarised as –

Acid + Metal →Salt + Hydrogen gas

The reaction between an acid and a base to give a salt and water is known as a neutralisation

reaction. In general, a neutralisation reaction can be written as –

Base + Acid →Salt + Water

The general reaction between a metal oxide and an acid can be written as –

Metal oxide + Acid →Salt + Water

Non-metallic oxides are acidic in nature

The electric current is carried through the solution by ions.

Bases which are soluble in water are called alkalis.

All bases do not dissolve in water. An alkali is a base that dissolves in water.

All acids generate H+ (aq) and all bases generate OH – (aq), we can view the neutralisation reaction

as follows –

Acid + Base → Salt + Water

H X + M OH →MX + HOH

H+(aq) + OH – (aq) →H2 O

The p in pH stands for ‘potenz’ in German, meaning power. On the pH scale we can measure pH

from 0 (very acidic) to 14 (very alkaline).

Our body works within the pH range of 7.0 to 7.8.

When pH of rain water is less than 5.6, it is called acid rain

The salt formed by the combination of hydrochloric acid and sodium hydroxide solution is called

sodium chloride. This is the salt that you use in food.

Sodium hydroxide: when electricity is passed through an aqueous solution of sodium chloride (called

brine), it decomposes to form sodium hydroxide. The process is called the chlor-alkali process.

Calcium sulphate hemihydrate called ‘Plaster of Paris’.

Chapter 7_6: Physical and Chemical Changes:

Changes can be of two types, physical and chemical.

Physical changes are changes in the physical properties of substances. No new substances

are formed in these changes. These changes may be reversible.

In chemical changes new substances are produced. „

Some substances can be obtained in pure state from their solutions by crystallisation.

Properties such as shape, size, colour and state of a substance are called its physical properties

physical properties.

For rusting, the presence of both oxygen and water (or water vapour) is essential. This process of

depositing a layer of zinc on iron is called galvanisation.

Stainless steel is made by mixing iron with carbon and metals like chromium, nickel and manganese.

It does not rust.

Large crystals of pure substances can be formed from their solutions. The process is called

crystallisation. It is an example of a physical change.

Chapter 10_1: Chemical Reactions and Equations

A chemical reaction has taken place – „

change in state

change in colour „

evolution of a gas

change in temperature

Chapter 8_3: SYNTHETIC FIBRES AND PLASTICS

Natural fibres like cotton, wool, silk, etc., are obtained from plants or animals. The synthetic fibres,

on the other hand, are made by human beings. That is why these are called synthetic or man-made

fibres.

Each small unit is actually a chemical substance. Many such small units combine to form a large

single unit called a polymer.

A synthetic fibre is also a chain of small units joined together. Each small unit is actually a chemical

substance. Many such small units combine to form a large single unit called a polymer. The word

‘polymer’ comes from two Greek words; poly meaning many and mer meaning part/unit. So, a

polymer is made of many repeating units

Polymers occur in nature also. Cotton, for example, is a polymer called cellulose. Cellulose is made

up of a large number of glucose units

A fibre having properties similar to that of silk. Such a fibre was obtained by chemical treatment of

wood pulp. This fibre was called rayon or artificial silk. Although rayon is obtained from a natural

source, wood pulp, yet it is a man-made fibre

Nylon is another man-made fibre. In 1931, it was made without using any natural raw material (from

plant or animal). It was prepared from coal, water and air. It was the first fully synthetic fibre

Polyester is another synthetic fibre. Fabric made from this fibre does not get wrinkled easily.

PET is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many

other useful products

We wear sweaters and use shawls or blankets in the winter. Many of these are actually not made

from natural wool, though they appear to resemble wool. These are prepared from another type of

synthetic fibre called acrylic.

All the synthetic fibres are prepared by a number of processes using raw materials of petroleum

origin, called petrochemicals

Polythene (Poly+ethene) is an example of a plastic. It is used for making commonly used polythene

bags.

Plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics.

Polythene and PVC are some of the examples of thermoplastics

There are some plastics which when moulded once, cannot be softened by heating. These are called

thermosetting plastics. Two examples are Bakelite and melamine. Bakelite is a poor conductor of

heat and electricity. It is used for making electrical switches, handles of various utensils, etc.

Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is

used for making floor tiles, kitchenware and fabrics which resist fire.

A material which gets decomposed through natural processes, such as action by bacteria, is called

biodegradable. A material which is not easily decomposed by natural processes is termed as non-

biodegradable.

Synthetic fibres and plastics, like natural fibres, are made of very large units called polymers.

Polymers are made up of many smaller units.

While natural fibres are obtained from plants and animals, synthetic fibres are obtained by

chemical processing of petrochemicals. Like natural fibres, these fibres can also be woven

into fabrics.

Synthetic fibres find uses ranging from many household articles like ropes, buckets,

furniture, containers, etc. to highly specialized uses in aircrafts, ships, spacecraft ’s,

healthcare, etc. Depending upon the types of chemicals used for manufacturing synthetic

fibres, they are named as Rayon, Nylon, Polyester and Acrylic.

The different types of fibres differ from one another in their strength, water absorbing

capacity, nature of burning, cost, durability, etc.

Today, life without plastics cannot be imagined. Be it home, or outside, plastic is

everywhere. The waste created by plastics is not environment friendly. On burning plastics

release poisonous gases. On dumping in the ground they may take years to degenerate. This

is because of their non-biodegradable nature.

We need to use synthetic fibres and plastics in such a manner that we can enjoy their good

qualities and at the same time minimise the environmental hazards for the living

communities.

As a responsible citizen remember the 4 R principles. Reduce, Reuse, Recycle and Recover.

Chapter 8_4: MATERIALS: METALS AND NON-METALS

Metals are lustrous whereas non-metals have no lustre.

Generally, metals are malleable and ductile. Non-metals do not have these properties.

Generally, metals are good conductors of heat and electricity but non-metals are poor

conductors.

On burning, metals react with oxygen to produce metal oxides which are basic in nature.

Non-metals react with oxygen to produce non- metallic oxides which are acidic in nature.

Some metals react with water to produce metal hydroxides and hydrogen gas. Generally,

non-metals do not react with water.

Metals react with acids and produce metal salts and hydrogen gas. Generally, non-metals do

not react with acids.

Some metals react with bases to produce hydrogen gas.

More reactive metals displace less reactive metals from their compounds in aqueous

solutions.

The property of metals by which they can be beaten into thin sheets is called malleability. This is a

characteristic property of metals

Iron rod, nail and copper wire are good conductors while rolled sulphur piece and coal piece are

poor conductors

The property of metal by which it can be drawn into wires is called ductility .

Since metals produce ringing sounds, they are said to be sonorous. The materials other than metals

are not sonorous

Some materials are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and

electricity. The materials which generally possess these properties are called metals. The examples

of metals are iron, copper, aluminium, calcium, magnesium, etc.

In contrast, materials like coal and sulphur are soft and dull in appearance. They are not sonorous

and are poor conductors of heat and electricity. These materials are called non-metals. The

examples of non-metals are sulphur, carbon, oxygen, phosphorus, etc.

Metals like sodium and potassium are soft and can be cut with a knife. Mercury is the only metal

which is found in liquid state at room temperature. These are exceptions.

The red litmus turns blue. So, oxide of magnesium is also basic in nature. In general, metallic oxides

are basic in nature.

The sulphurous acid turns blue litmus paper red. Generally, oxides of non-metals are acidic in

nature.

Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated

in the reaction. It is, therefore, stored in kerosene

Phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of

phosphorus with atmospheric oxygen, it is stored in water.

Non-metals generally do not react with acids but metals react with acids and produce hydrogen gas

that burns with a ‘pop’ sound.

Metals react with sodium hydroxide to produce hydrogen gas. Reactions of non-metals with bases

are complex. Zinc is more reactive than copper and iron.

A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a

more reactive metal.

A substance cannot be broken down further by chemical reactions, by cooling, heating, or by

electrolysis, it is called ‘element’. Sulphur is an element. So is iron. Carbon, too, is an element. The

smallest unit of an element is atom.

There are no more than 92 naturally occurring elements.

Most of the elements are metals. Less than 20 are non-metals. A few are metalloids which possess

characters of both metals and non-metals.

Chapter 10_3: Metals and Non-metals

Metals, in their pure state, have a shining surface. This property is called metallic lustre

metals can be beaten into thin sheets. This property is called malleability. Did you know that gold

and silver are the most malleable metals

The ability of metals to be drawn into thin wires is called ductil ity

It is because of their malleability and ductility that metals can be given different shapes according to

our needs

metals are good conductors of heat and have high melting points. The best conductors of heat are

silver and copper. Lead and mercury are comparatively poor conductors of heat

The metals that produce a sound on striking a hard surface are said to be sonorous. Can you now say

why school bells are made of metals

the wires that carry current in your homes have a coating of polyvinylchloride (PVC) or a rubber-like

material. Why are electric wires coated with such substances

The non-metals are either solids or gases except bromine which is a liquid

non-metals are carbon, sulphur, iodine, oxygen, hydrogen, etc. The non-metals are either solids or

gases except bromine which is a liquid

All metals except mercury exist as solids at room temperature

Iodine is a non-metal but it is lustrous

Carbon is a non-metal that can exist in different forms. Each form is called an allotrope. Diamond, an

allotrope of carbon, is the hardest natural substance known and has a very high melting and boiling

point. Graphite, another allotrope of carbon, is a conductor of electricity

Alkali metals (lithium, sodium, potassium) are so soft that they can be cut with a knife. They have

low densities and low melting points

Most non-metals produce acidic oxides when dissolve in water. On the other hand, most metals,

give rise to basic oxides

Almost all metals combine with oxygen to form metal oxides. Metal + Oxygen →Metal oxide

some metal oxides, such as aluminium oxide, zinc oxide, etc., show both acidic as well as basic

behaviour. Such metal oxides which react with both acids as well as bases to produce salts and water

are known as amphoteric oxides

Most metal oxides are insoluble in water but some of these dissolve in water to form alkalis. Sodium

oxide and potassium oxide dissolve in water to produce alkalis

Anodising is a process of forming a thick oxide layer of aluminium.

metals react with acids to give a salt and hydrogen gas

Aqua regia,(Latin for ‘royal water’) is a mixture of concentrated hydrochloric acid and concentrated

nitric acid in the ratio of 3:1. Aqua regiais a highly corrosive, fuming liquid is able to dissolve gold and

platinum.

The compounds formed in this manner by the transfer of electrons from a metal to a non-metal are

known as ionic compounds or electrovalent compounds

The elements or compounds, which occur naturally in the earth’s crust, are known as minerals. At

some places, minerals contain a very high percentage of a particular metal and the metal can be

profitably extracted from it. These minerals are called ores

Ores mined from the earth are usually contaminated with large amounts of impurities such as soil,

sand, etc., called gangue.

the reaction of iron(III) oxide (Fe 2O3 ) with aluminium is used to join railway tracks or cracked

machine parts. This reaction is known as the thermit reaction.

The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This

process is known as roasting

The carbonate ores are changed into oxides by heating strongly in limited air. This process is known

as calcination.

method for refining impure metals is electrolytic refining

Electrolytic refining of copper. The electrolyte is a solution of acidified copper sulphate. The anode is

impure copper, whereas, the cathode is a strip of pure copper. On passing electric current, pure

copper is deposited on the cathode

The rusting of iron can be prevented by painting, oiling, greasing, galvanising, chrome plating,

anodising or making alloys.

Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer

of zinc.

If one of the metals is mercury, then the alloy is known as an amalgam.

Chapter 9_1: Matter IN OUR SURROUNDINGS

Matter based on their physical properties and chemical nature

MATTER IS MADE UP OF PARTICLES, PARTICLES OF MATTER HAVE SPACE BETWEEN THEM, AND

PARTICLES OF MATTER ARE CONTINUOUSLY MOVING.

Gases are highly compressible as compared to solids and liquids. The liquefied petroleum gas (LPG),

compressed natural gas (CNG).

Water can exist in three states of matter–

• Solid, as ice • liquid, as the familiar water, and • gas, as water vapour.

The melting point of ice is 273.16 K*

Solid CO2 gets converted directly to gaseous state on decrease of pressure to 1 atmosphere*

without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice

Five states of matter: Solid, Liquid, Gas, Plasma and Bose-Einstein Condensate

Plasma: The state consists of super energetic and super excited particles. These particles are in the

form of ionised gases.

Bose-Einstein Condensate: In 1920, Indian physicist Satyendra Nath Bose had done some

calculations for a fifth state of matter.

Building on his calculations, Albert Einstein predicted a new state of matter – the Bose Einstein

Condensate (BEC). In 2001, Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman of USA received

the Nobel Prize in physics for achieving “Bose-Einstein condensation”.

Matter is made up of small particles.

The matter around us exists in three states— solid, liquid and gas.

The forces of attraction between the particles are maximum in solids, intermediate in liquids

and minimum in gases.

The spaces in between the constituent particles and kinetic energy of the particles are

minimum in the case of solids, intermediate in liquids and maximum in gases.

The arrangement of particles is most ordered in the case of solids, in the case of liquids

layers of particles can slip and slide over each other while for gases, there is no order,

particles just move about randomly.

The states of matter are inter-convertible. The state of matter can be changed by changing

temperature or pressure.

Sublimation is the change of gaseous state directly to solid state without going through

liquid state, and vice versa.

Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid change into

vapour state.

Evaporation is a surface phenomenon. Particles from the surface gain enough energy to

overcome the forces of attraction present in the liquid and change into the vapour state.

The rate of evaporation depends upon the surface area exposed to the atmosphere, the

temperature, the humidity and the wind speed.

Evaporation causes cooling.

Latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at

atmospheric pressure at its boiling point.

Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into

liquid at its melting point

Chapter 9_2: Matter around us Pure:

Solid solutions (alloys) and gaseous solutions (air)

Alloys: Alloys are homogeneous mixtures of metals and cannot be separated into their components

by physical methods.

Properties of a solution

A solution is a homogeneous mixture.

The particles of a solution are smaller than 1 nm (10 -9 metre) in diameter. So, they cannot

be seen by naked eyes.

Because of very small particle size, they do not scatter a beam of light passing through the

solution. So, the path of light is not visible in a solution.

The solute particles cannot be separated from the mixture by the process of filtration. The

solute particles do not settle down when left undisturbed, that is, a solution is stable

When no more solute can be dissolved in a solution at a given temperature, it is called a saturated

solution.

Properties of a suspension

The particles of a suspension can be seen by the naked eye.

The particles of a suspension scatter a beam of light passing through it and make its path

visible.

The solute particles settle down when a suspension is left undisturbed, that is, a suspension

is unstable. They can be separated from the mixture by the process of filtration

This scattering of a beam of light is called the Tyndall effect after the name of the scientist who

discovered this effect.

Properties of a colloid

A colloid is a heterogeneous mixture.

The size of particles of a colloid is too small to be individually seen by naked eyes.

Colloids are big enough to scatter a beam of light passing through it and make its path

visible.

They do not settle down when left undisturbed, that is, a colloid is quite stable.

They cannot be separated from the mixture by the process of filtration. But, a speci al

technique of separation known as centrifugation (perform activity 2.5), can be used to

separate the colloidal particles

Sometimes the solid particles in a liquid are very small and pass through a filter paper. For such

particles the filtration technique cannot be used for separation. Such mixtures are separated by

centrifugation.

Chromatography is the technique used for separation of those solutes that dissolve in the same

solvent

Air is a homogeneous mixture and can be separated into its components by f ractional distillation.

The crystallisation method is used to purify solids. Crystallisation is a process that separates a pure

solid in the form of its crystals from a solution

Mercury is the only metal that is liquid at room temperature

The number of elements known at present is more than 100.

Ninety-two elements are naturally occurring and the rest are manmade.

Majority of the elements are solid.

Eleven elements are in gaseous state at room temperature.

Two elements are liquid at room temperature–mercury and bromine.

Elements, gallium and cesium become liquid at a temperature slightly above room

temperature (303 K)

Summary:

Chapter 9_3: ATOMS AND MOLECULES

Democritus called these indivisible particles atoms (meaning indivisible)

Antoine L. Lavoisier laid the foundation of chemical sciences by establishing two important laws of

chemical combination

Law of conservation of mass states that mass can neither be created nor destroyed in a chemical

reaction

In a compound such as water, the ratio of the mass of hydrogen to the mass of oxygen is always 1:8,

whatever the source of water. Thus, if 9 g of water is decomposed, 1 g of hydrogen and 8 g of

oxygen are always obtained. Similarly in ammonia, nitrogen and hydrogen are always present in the

ratio 14:3

This led to the law of constant proportions which is also known as the law of definite proportions.

This law was stated by Proust as “In a chemical substance the elements are always present in

definite proportions by mass”

Valency can be used to find out how the atoms of an element will combine with the atom(s) of

another element to form a chemical compound

The combining power (or capacity) of an element is known as its valency. Valency can be used to find

out how the atoms of an element will combine with the atom(s) of another element to form a

chemical compound.

Summary:

Chapter 9_4: Structure of the atom

Summary:

Chapter 8_5: Coal and Petroleum:

As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called

carbonisation

Since it was formed from the remains of vegetation, coal is also called a fossil fuel.

These days, bitumen, a petroleum product, is used in place of coal -tar for metalling the roads

Coal gas was used for street lighting for the first time in London in 1810 and in New York around

1820. Now days, it is used as a source of heat rather than light.

Petrol and diesel are obtained from a natural resource called petroleum

The world’s first oil well was drilled in Pennsylvania, USA, in 1859. Eight years later, in 1867, oil

was stuck at Makum in Assam. In India, oil is found in Assam, Gujarat, and Mumbai High and in the

river basins of Godavari and Krishna.

Many useful substances are obtained from petroleum and natural gas. These are termed as

‘Petrochemicals’. These are used in the manufacture of detergents, fibres (polyester, nylon, acrylic

etc.), polythene and other man-made plastics. Hydrogen gas obtained from natural gas, is used in

the production of fertilisers (urea). Due to its great commercial importance, petroleum is also called

‘black gold’.

India has vast reserves of natural gas. In our country, natural gas has been found in Tripura,

Rajasthan, and Maharashtra and in the Krishna Godavari delta.

In India, the Petroleum Conservation Research Association (PCRA) advises people how to

save petrol/diesel while driving.

Coal, petroleum and natural gas are fossil fuels.

Fossil fuels were formed from the dead remains of living organisms millions of years ago.

Fossil fuels are exhaustible resources. Coke, coal tar and coal gas are the products of coal.

Petroleum gas, petrol, diesel, kerosene, paraffin wax, lubricating oil are obtained by refining

petroleum.

Coal and petroleum resources are limited. We should use them judiciously.

Chapter 8_6: COMBUSTION AND FLAME

Magnesium burns to form magnesium oxide and produces heat and light

A chemical process in which a substance reacts with oxygen to give off heat is called combustion.

The substance that undergoes combustion is said to be combustible. It is also called a fuel. The fuel

may be solid, liquid or gas. Sometimes, light is also given off during combustion, either as a flame or

as a glow

Magnesium and charcoal are combustible substances

In the sun, heat and light are produced by nuclear reactions.

The lowest temperature at which a substance catches fire is called its ignition temperature

For fires involving electrical equipment and inflammable materials like petrol, carbon dioxide (CO 2)

is the best extinguisher. CO 2 , being heavier than oxygen, covers the fire like a blanket. Since the

contact between the fuel and oxygen is cut off, the fire is controlled. The added advantage of CO 2 is

that in most cases it does not harm the electrical equipment

Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines.

Spontaneous forest fires are sometimes due to the heat of the sun or due to lightning strike.

The amount of heat energy produced on complete combustion of 1 kg of a fuel is call ed its calorific

value. The calorific value of a fuel is expressed in a unit called kilojoule per kg(kJ/kg).

The substances which burn in air are called combustible.

Oxygen (in air) is essential for combustion.

During the process of combustion, heat and light are given out.

Ignition temperature is the lowest temperature at which a combustible substance catches

fire.

Inflammable substances have very low ignition temperature.

Fire can be controlled by removing one or more requirements essential for producing fire.

Water is commonly used to control fires.

Water cannot be used to control fires involving electrical equipments or oils.

There are various types of combustions such as rapid combustion, spontaneous combustion,

explosion, etc.

There are three different zones of a flame -dark zone, luminous zone and non-luminous

zone.

An ideal fuel is cheap, readily available, readily combustible and easy to transport. It has high

calorific value. It does not produce gases or residues that pollute the environment.

Fuels differ in their efficiency and cost.

Fuel efficiency is expressed in terms of its calorific value which is expressed in units of

kilojoule per kg.

Unburnt carbon particles in air are dangerous pollutants causing respiratory problems.

Incomplete combustion of a fuel gives poisonous carbon monoxide gas.

Increased percentage of carbon dioxide in air has been linked to global warming.

Oxides of sulphur and nitrogen produced by the burning of coal, diesel and petrol cause acid

rain which is harmful for crops, buildings and soil.

Chapter 10_4: Carbon and its Compound

The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates,

hydrogencarbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide

The shared pair of electrons is said to constitute a single bond between the two hydrogen atoms.

The two electrons contributed by each oxygen atom give rise to two shared pairs of electrons. This is

said to constitute a double bond between the two atoms

In order to attain an octet, each nitrogen atom in a molecule of nitrogen contributes three electrons

giving rise to three shared pairs of electrons. This is said to constitute a triple bond between the two

atoms.

bonds which are formed by the sharing of an electron pair between two atoms are known as

covalent bonds.

Both diamond and graphite are formed by carbon atoms

In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three -

dimensional structure

In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a

hexagonal array

4.2 VERSATILE NATURE OF CARBON

Carbon has the unique ability to form bonds with other atoms of carbon, giving rise to large

molecules. This property is called catenation.

Compounds of carbon, which are linked by only single bonds between the carbon atoms are called

saturated compounds. Compounds of carbon having double or triple bonds between their carbon

atoms are called unsaturated compounds.

Since carbon has a valency of four, it is capable of bonding with four other atoms of carbon or atoms

of some other mono-valent element.

compounds with identical molecular formula but different structures are called structural isomers

All these carbon compounds which contain just carbon and hydrogen are called hydrocarbons.

Among these, the saturated hydrocarbons are called alkanes. The unsaturated hydrocarbons which

contain one or more double bonds are called alkenes. Those containing one or more triple bonds are

called alkynes

compounds, the element replacing hydrogen is referred to as a heteroatom. These heteroatoms

confer specific properties to the compound, regardless of the length and nature of the carbon chain

and hence are called functional groups

a series of compounds in which the same functional group substi tutes for hydrogen in a carbon

chain is called a homologous series

The general formula for alkenes can be written as C nH2n , where n = 2, 3, 4.

Saturated hydrocarbons will generally give a clean flame while unsaturated carbon compounds will

give a yellow flame with lots of black smoke.

the formation of oxides of sulphur and nitrogen which are major pollutants in the environment.

substances are capable of adding oxygen to others. These substances are known as oxidising agents

Ethanol is commonly called alcohol and is the active ingredient of all alcoholic drinks.

In addition, because it is a good solvent, it is also used in medicines such as tincture iodine, cough

syrups, and many tonic

Ethanol is also soluble in water in all proportions.

Sugarcane plants are one of the most efficient convertors of sunlight into chemical energy.

Sugarcane juice can be used to prepare molasses which is fermented to give alcohol (ethanol).

Esters are sweet-smelling substances. These are used in making perfumes and as flavouring agents.

Esters react in the presence of an acid or a base to give back the alcohol and carboxylic acid. This

reaction is known as saponification because it is used in the preparation of soap.

Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids

Chapter 10_5: Periodic Classification of Elements