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• Everything in the universe, living or non-living, is made of a combination of a few

basic substances called elements.

• An element is the simplest form of matter composed of atoms having identical number

of protons in each nucleus.

• An atom is the smallest fragment of an element that can take part in a chemical action.

• The theory that all matter is made up of small particles (atoms) was put forward by

John Dalton. He defi ned the atom as the smallest neutral particle of matter which

may have independent existence. It consists of a central nucleus (made up of protons

which are positively charged and neutrons which are neutral particles) surrounded by

orbiting electrons.

• Atoms of diff erent elements diff er from one another in the number of protons and

neutrons in the nucleus and the number of electrons surrounding the nucleus.

• The number of electrons is however, always equal to the number of protons which is

known as the elements’ atomic number.

• Periodic Table: The chemical elements can be arranged in order of increasing atomic

number in such a way that elements with similar properties appear together. Such an

arrangement is called a periodic table.

— Lightest (simplest) element (naturally occurring)—Hydrogen (Element 1)

— Most complex element (naturally occurring)—Uranium (Element 92)

— Commonest element (lithosphere)—Oxygen

— Commonest element (atmosphere)—Nitrogen

— Commonest element (universe)—Hydrogen

— Rarest element—Astatine

— Lightest element (metal)—Lithium

— Heaviest element (gas)—Radon

— Lightest element (gas)—Hydrogen

• Hydrogen has atomic number 1, with 1 proton and 1 electron. Uranium, the heaviest naturally occurring element has atomic number 92, having 92 protons, 92 electrons and 146 neutrons. 

• All elements heavier than uranium are man-made and are produced in nuclear reactors

or accelerators or isolated from debris of atomic explosions (transuranic).

The new elements are:

• The Russian scientist Dimitri Mendeleev devised the periodic table in 1869. At that

time there were only 59 elements in it but had 33 empty spaces that implied that there

were elements still to be discovered.

• Dimitri gave these still-hypothetical elements names like ‘ekasilicon,’ ‘ekaaluminum’

and ‘ekaboron,’ based on their expected similarities to known substances; the spaces

were fi lled by germanium, gallium and scandium, respectively. (‘Eka-’ is a Sanskrit

prefi x meaning ‘one,’ so you can think of the names as silicon 1, aluminum 1 and so on.)

• By year 1939, all of Mendeleev’s boxes had been fi lled in; the last one was ‘ekacesium,’

now called francium.

• There are around 118 known elements, out of which 92 are naturally occurring and

26 are man-made elements, created by nuclear bombardment.

• The man-made elements are known as transuranic. Neptunium (Element 93) was the

first such element discovered in 1940.

• Since Lawrencium (Lr) in 1961, the following new elements have been discovered:

1. Rutherfordium (Rf) Atomic No. 104

2. Dubnium (Db) Atomic No. 105

3. Seaborgium (Sg) Atomic No. 106

4. Bohrium (Bh) Atomic No. 107

5. Hassium (Hs) Atomic No. 108

6. Meitnerium (Mt) Atomic No. 109

 7. Darmstadtium (Ds) Atomic No. 110

 8. Roentgenium (Rg) Atomic No. 111

 9. Copernicium (Cr) Atomic No. 112

10. Flerovium (Fl) Atomic No. 114

11. Livermorium (Lv) Atomic No. 116.

• Four elements: Ununtrium (Element 113), Ununpentium (Element 115); Ununseptium

(Element 117) and Ununoctium (Element 118) are still unconfi rmed discoveries.

• Russian scientists had claimed the discovery of element 115 back in 2003 but the International

Union of Pure and Applied Chemistry. Chemistry’s equivalent of the International

Astronomical Union which famously demoted Pluto from planet status in 2006 wouldn’t

acknowledge it without a confi rming experiment from another team. The Helmholtz Center’s

work must still be reviewed by both the I.U.P.A.C. and the International Union of Pure and

Applied Physics but ununpentium is now a step closer to inclusion on the periodic table. If

that happens, the International Union will assign it a permanent, offi cial name.

• I.U.P.A.C. has already signed off on element 116 (livermorium), element 117

(ununseptium) and element 118 (ununoctium), although the latter two haven’t been

assigned permanent names yet. Ununoctium’s half life is just 0.89 milliseconds.


• Elements are classifi ed in two main classes are (i) Metals (for example, lead, gold,

mercury, etc.) and (ii) Non-metals (for example, chlorine, bromine, carbon, etc.)

• Some elements behave chemically both as metals and non-metals are called metaloids,

for example, boron, silicon, germanium and antimony.

• Nobel Gases: There are also some elements which are neither metals nor non-metals.

These elements are called noble gases and are present in the atmosphere as helium, argon, neon, krypton, radon and xenon. 


• There are two types of elements—metals and non-metals. About 80% of known Elements are metals.

Elements which are hard, ductile, brittle and malleable; possess lustre and conduct

heat and electricity are termed metals. All metals are solids except mercury and

gallium which are liquids at room temperature. Metals usually have high melting and boiling points. 

Chemical Nature of Metals

• Usually metals have the tendency to lose electrons and while reacting with acids,

usually replace hydrogen in dilute non-oxidizing acids like hydrochloric acid (HCl)

and sulphuric acid (H2SO4).

• Exceptions are copper, silver and gold. Chlorides of metals are true salts and oxides of

metals are usually basic. Hydrides of metals are ionic, unstable and reactive.

• Although all the metals are reactive, that is, they are acted upon by common reagents

like oxygen (air), hydrogen, halogens, sulphur, water, acids, etc., the extent of reaction

is diff erent in the case of each metal.

• Only gold, platinum and silver are not aff ected by air and water under ordinary

conditions and are known as free metals.

• Various compounds of metal called minerals are found in nature and can be mined.

• The mineral from which metal can be extracted economically is called ore and the process of extraction of metals from their ores is called metallurgy which involves: 

—Calcination: The process of heating the concentrated ore in the absence of air.

—Roasting: The process of heating the ore in excess air.

—Smelting: The process by which roasted ore is mixed with coke and heated in a

furnace to obtain free metal.

Steel and Iron

• Steel is a form of iron. To make steel from iron, the carbon content is bought down

from 5% to 0.5–1.5%.

• Heat Treatment of Steel

—Quenching: If steel is heated to bright redness and then suddenly cooled in water or

oil it becomes extraordinarily hard and brittle.

—Tempering: By controlled heating (250–325°C) of quenched steel its brittleness can

be removed without aff ecting its hardness.

—Annealing: Steel is heated to a temperature well below red hot and then cooled turns it soft and the process is called annealing. 

Rusting of Iron

• Majority of metals occur in nature in the combined form and are extracted from their ores.  

• When these metals are exposed to atmospheric conditions they have a tendency to return to their original form. This change is called corrosion of metals and in the case of iron it is known as rusting. 

• Rusting consists of the formation of hydrated ferric oxide. For rusting water and oxygen are essential in the absence of water or electrolyte rusting does not occur.  

• The process involves addition of hydrogen and oxygen elements and it is found that mass of an iron rod increases by rusting. Rusting is prevented by coating the surface of  

iron with metals or non-metals or by alloying. The coating of another metal is known as electroplating or hot dipping.

In electroplating chromium or nickel is used. When a coat of zinc is applied on an iron

surface by the hot-dipping process it is known as galvanizing.


• Non-metals are electro-negative elements which have a tendency to gain one or

more electrons to form negative ions called anions. All non-metals generally exist as

powders or gases, except bromine which is liquid under normal conditions.

• Non-metals are non-lustrous and are bad conductors of heat and electricity. They

cannot be hammered into sheets or drawn into wires like metals. The melting point of

non-metals is lower than that of metals.


Alloys are homogeneous mixtures of two or more metals and non-metals and have more

commercial utility than some of the constituent elements. The following table lists some

of the commercially important alloys.

Alloys of Some Important Elements

Aluminum Alloys

 1. AA-8000: used for building wire

 2. Al-Li (aluminum, lithium, some-

times mercury)

 3. Alnico (aluminum, nickel, copper)

 4. Duralumin (copper, aluminum)

 5. Magnalium (aluminum, 5% magne-


 6. Magnox (magnesium oxide, alumi-


 7. Nambe (aluminum plus seven other

unspecifi ed metals

 8. Silumin (aluminum, silicon)

 9. Zamak (zinc, aluminum, magnesium,


10. Aluminum forms other complex

 alloys with magnesium, manganese

and platinum

Bismuth Alloys

 1. Wood’s metal (bismuth, lead, tin,


 2. Rose metal (bismuth, lead, tin)

 3. Field’s metal

 4. Cerrobend

Cobalt Alloys

 1. Stellite (cobalt, chromium, tungsten

or molybdenum, carbon)

 2. Talonite (cobalt, chromium)

 3. Ultimet (cobalt, chromium, nickel,

molybdenum, iron, tungsten)

Copper Alloys

 1. Beryllium copper (copper, beryllium)

 2. Billon (copper, silver)

 3. Brass (copper, zinc) [Calamine brass

(copper, zinc); Chinese silver (cop-

per, zinc); Dutch metal (copper, zinc);

Gilding metal (copper, zinc); Muntz

metal (copper, zinc); Pinchbeck

(copper, zinc); Prince’s metal (copper,

zinc); Tombac (copper, zinc)]

 4. Bronze (copper, tin, aluminum or any

other element) [Aluminum bronze

(copper, aluminum); Arsenical bronze

(copper, arsenic); Bell metal (copper,

tin); Florentine bronze (copper,

aluminum or tin); Glucydur (beryllium,

copper, iron); Guani n (likely a man-

ganese bronze of copper, manganese,

with iron sulfi des and other sulfi des);

Gunmetal (copper, tin, zinc); Phosphor

bronze (copper, tin and phosphorus);

Ormolu (Gilt Bronze) (copper, zinc);

Speculum metal (copper, tin)]

 5. Constantan (copper, nickel)

 6. Copper-tungsten (copper, tungsten)

 7. Corinthian bronze (copper, gold,


8. Cunife (copper, nickel, iron)

 9. Cupronickel (copper, nickel)

10. Cymbal alloys (Bell metal)

(copper, tin)

11. Devarda’s alloy (copper,

aluminum, zinc)

12. Electrum (copper, gold, silver)

13. Hepatizon (copper, gold, silver)

14. Heusler alloy (copper, manganese, tin)

15. Manganin (copper, manganese,


16. Nickel silver (copper, nickel)

17. Nordic gold (copper, aluminum,

zinc, tin)

18. Shakudo (copper, gold)

19. Tumbaga (copper, gold)

Gallium Alloys

 Galinstan (gallium, indium, tin)

Gold Alloys

 1. Electrum (gold, silver, copper)

 2. Tumbaga (gold, copper)

 3. Rose gold (gold, copper)

 4. White gold (gold, nickel, palladium

or platinum)

Indium Alloys

Field’s metal (indium, bismuth, tin)

Iron or Ferrous Alloys

 1. Steel (carbon) [Stainless steel

(chromium, nickel); {AL-6XN; Al-

loy 20; Celestrium; Marine grade

stainless; Martensitic stainless steel;

Surgical stainless steel (chromium,

 molybdenum, nickel)}; Silicon steel

(silicon); Tool steel (tungsten or

manganese); Bulat steel; Chromoly

 (chromium, molybdenum); Crucible

steel; Damascus steel; High speed

steel; Maraging steel; Wootz steel]

 2. Iron [Anthracite iron (carbon); Cast

iron (carbon); Pig iron (carbon);

Wrought iron (carbon)]

 3. Fernico (nickel, cobalt)

 4. Elinvar (nickel, chromium)

 5. Invar (nickel)

 6. Kovar (cobalt)

 7. Spiegeleisen (manganese, carbon,


 8. Ferroalloys [Ferroboronl;

Ferrochrome (chromium);

Ferromagnesium; Ferromanganese;

Ferromolybdenum; Ferronickel;

Ferrophosphorus; Ferrotitanium;

Ferrovanadium; Ferrosilicon]

Lead Alloys

 1. Antimonial lead (lead, antimony)

 2. Molybdochalkos (lead, copper)

 3. Solder (lead, tin)

 4. Terne (lead, tin)

 5. Type metal (lead, tin, antimony)

Magnesium Alloys

 1. Magnox (magnesium, aluminum)

 2. T-Mg-Al-Zn (Bergman phase)

 3. Elektron

Mercury Alloys

 Amalgam (mercury with just about any

metal except platinum)

Nickel Alloys

 1. Alumel (nickel, manganese,

 aluminum, s ilicon)

 2. Chromel (nickel, chromium)

 3. Cupronickel (nickel, bronze,


 4. German silver (nickel, copper, zinc)

 5. Hastelloy (nickel, molybdenum,

chromium, sometimes tungsten)

 6. Inconel (nickel, chromium, iron)

 7. Monel metal (copper, nickel, iron,


 8. Mu-metal (nickel, iron)

 9. Ni-C (nickel, carbon)

10. Nichrome (chromium, iron,


11. Nicrosil (nickel, chromium, silicon,


12. Nisil (nickel, silicon)

13. Nitinol (nickel, titanium, shape

 memory a lloy)

Potassium Alloys

 1. KLi (potassium, lithium)

 2. NaK (sodium, potassium)

Rare Earth Alloys

Mischmetal (various rare earths)

Silver Alloys

 1. Argentium sterling silver (silver,

copper, germanium)

 2. Billon (copper or copper bronze,

sometimes with silver)

 3. Britannia silver (silver, copper)

 4. Electrum (silver, gold)

 5. Goloid (silver, copper, gold)

 6. Platinum sterling (silver, platinum)

 7. Shibuichi (silver, copper)

 8. Sterling silver (silver, copper)

Tin Alloys

 1. Britannium (tin, copper, antimony)

 2. Pewter (tin, lead, copper)

 3. Solder (tin, lead, antimony)

Titanium Alloys

 1. Beta C (titanium, vanadium,

 chromium, other metals)

 2. 6al-4v (titanium, aluminum,


Uranium Alloys

 1. Staballoy (depleted uranium with

titanium or molybdenum)

 2. Uranium may also be alloyed with


Zinc Alloys

 1. Brass (zinc, copper)

 2. Zamak (zinc, aluminum, magnesium,


Zirconium Alloys

Zircaloy (zirconium and tin, sometimes

with niobium, chromium, iron, nickel)

Table 10.1 Important Alloys and Their Uses

Alloy Composition Commercial Utility



Tin = 91%, Antimony = 7%

Copper = 3%

Used in bearings because of its low

measure of friction with steel

Bell Metal Copper 77%, Tin = 23% Casting of bells

Monel Nickel = 60%, Copper = 33%,

Iron = 7%

Corrosion-resistant containers

Magnalium Aluminium = 85–99%;

Magnesium = 1–15%

Used in making balance beams and

light instruments

Duralumin Aluminium = 95%, Copper = 4%,

Magnesium <1%,

Manganese = 0.5%

Used in the production of airships,

pressure cookers, railroad cars and

machinery because of its high strength

and resistance to corrosion.

Bronze Copper = 75–90%,

Tin (Sn) = 10–25%

Utensils, coins, medals and statues,

heavy gears, tools electrical hardware



Bronze with a small amount of


Springs (normal and electrical) and

Boat propellers.



Copper = 88–90%

Aluminium = 10–12%

In the manufacture of utensils,

decorative articles like photo frames,

coins and jewellery

Brass Copper = 60–80%

Zinc = 20–40%

Utensils, inexpensive jewellery, hose

nozzles and couplings, standing dies,

condenser sheets and cartridges

Gun metal Copper = 85-90%, Tin = 8 –12%

Zinc = 1–3%

Guns, gears, castings

Alloy Composition Commercial Utility



Copper = 75%, Nickel = 25% In the making of coins also

known as ‘Coin Metal’

Solder Lead = 50%, Tin = 50% For soldering joining two metals to

each other



Iron = 73%, Carbon = 1%

Chromium= 18%, Nickel= 8%

In the manufacture of utensils,

automobile parts, cycle parts, cutlery

Invar Iron (Fe) = 63%, Carbon = 1%

Nickel (Ni) = 36%

In the manufacture of meter scales

measuring tapes, pendulum rods

Duriron Iron = 84.7%, Carbon = 0.8%

Silicon = 14.5%

Laboratory plumbing



Iron= 75–81%, Tungsten = 14 –20%,

Chromium = 4%, Carbon = 1%

For making high speed cutting tools



Silver = 92.5%, Copper 7.5% Jewellery, art objects etc.

Type Metal Lead = 75-90%, Antimony = 2–18%

Tin in trace quantities.

Used to make type characters for

printing; also used for making

decorative objects like statuettes and



• Minerals are naturally occurring chemical compounds of fixed composition and

characteristic, physical form and properties. A few minerals consist of only one element.

For example, graphite and diamond (both forms of carbon), sulphur and gold.

• Most minerals, however are a combination of two or more elements as in halite or

rock salt (NaCl). The most common group of minerals are Silicates, oxides, sulphides,

halides, carbonate.

• Minerals are of two types, namely, metallic or ore and non-metallic, for example,

carbon, sulphur, etc. (See table)

Table 10.2 Common Minerals

Name of the

Mineral Composition Commercial Utility

Albite Sodium aluminium


Glass, ceramics

Anhydrite Calcium sulphate Cement, fertilizers, chemicals

Anorthite Calcium aluminium


Glass, ceramics

Apatite Calcium phosphate Phosphate,

fl our-phosphate or Fertilizers, gemstones



• The atoms of an element, the smallest component seldom exist singly. They usually

join up with atoms of other elements to form a molecule of a compound. For example,

two atoms of oxygen combine to form a molecule of oxygen written as O2, O being the symbol of oxygen and 2 the number of atoms combined.  

• In the formulation of a compound, 2 atoms of iron (Fe), for example, may combine with 3 atoms of oxygen to form a molecule of ferric oxide (Fe2O3). 

• It has been estimated that there are 40,40,000 described compounds of which 63,000 are in common use. 

Chemical Reaction and Chemical Change

• Chemical change happens everywhere all the time, for example, when coal burns,

when iron rusts, when beer ferments, when concrete and cement set or when food is digested to give energy, etc.  

• When coal burns, carbon and hydrogen compounds within it combine with the oxygen

of the air to form carbon dioxide (CO2) and water vapours.

• Thus original constituent chemicals called reactants are converted into diff erent

substances called products which have diff erent properties.

Characteristics of Chemical Change

1. As seen above, in a chemical change the resultant product has diff erent properties as against that of the reactants. 

2. Conservation of Mass: For matter can neither be created nor destroyed during a

chemical reaction. In the above example the mass of coal and oxygen which combine

during combustion is exactly equal to the mass of carbon dioxide, water vapour and ash produced. 

3. When substances are formed in diff erent ways, that is, by diff erent chemical reactions,

it always has the same composition. In carbon dioxide (CO2), for example, no matter

how it is formed, carbon (C) and oxygen (O) are always in the ratio of 3:8 by mass.

4. In a chemical reaction, energy is given out or absorbed. For example, When coal burns

in air, energy in the form of heat and light is given out. On the other hand, when carbon

and sulphur are made to combine, heat is absorbed in this process.

Chemical Equation

• Chemical change can be represented by an equation, for example, the combustion of

carbon (C) in oxygen (O) to form carbon dioxide (CO2) can be shown as:

C + O2 → CO2

• The subscripts show that there are two atoms in an oxygen molecule.

• When hydrogen (H) and chlorine (Cl) react to form hydrogen chloride, the equation

will be

H2 + Cl2 → 2 HCl

• Note that two must be added before HCl on the right to balance the equation. The

equation shows that one molecule containing two hydrogen atoms plus one molecule

containing two chloride atoms react to form two molecules of hydrogen chloride.

Acid-base Reaction: One of the most common chemical reactions is double decomposition,

a process in which two compounds react together to form two new compounds.

For example, Magnesium sulphate (MgSO4) reacts with the solution of caustic soda

(NaOH) to form sodium sulphate (Na2 SO4) and antacid magnesium hydroxide (Mg(OH) 2)

MgSO4 + 2NaOH → Na2SO4 + Mg(OH)2

Oxidation and Reduction: Another common chemical reaction is oxidation. Originally it

meant combination of a substance with oxygen. However, now the term covers all analogous

reactions in which substances combine with other elements and lose electrons in the process.

• Oxidation is always accompanied simultaneously with reduction in which electrons are gained. 

E .g. Action of hydrogen (H2) with copper oxide (CuO)

CuO + H2 → Cu + H2O

• The oxide (CuO) is reduced to copper (Cu), the copper gains electrons in the reduction.

• Chemical reactions may take place either slowly—for example, rusting—or quickly as in an explosion. 

• Rate of chemical reaction can he greatly increased by the presence of a catalyst—a

substance which infl uences the reaction but does not change with it.


• Is a colourless and tasteless gaseous mixture of nitrogen (78%), oxygen (21%) with lesser

amounts (say traces) of argon. carbon dioxide, neon, helium, ozone and other gases.

• Air also contains water vapour and pollutants enveloping the earth. Being a mixture

(not compound) its composition varies from one place to another.

• Its constituents can be separated and it can be prepared by mixing oxygen and nitrogen.

Air is a bad conductor of heat.

• Of its constituents, oxygen helps in burning of substances and respiration and nitrogen

dilutes the action of oxygen.

• Carbon dioxide is added to the atmosphere through burning and also through respiration

and water vapour is formed during evaporation from the sea, rivers, ponds, etc.

Water Vapour in the Air: Air contains about 0.4% of water vapour.

• If we place a glass containing ice cubes in the open air, the outer surface of the glass

gets covered with water droplets. This is due to the condensation of water vapour, from

the atmospheric air on the cooler surface of the glass.

Carbon Dioxide: Air contains about 0.03% carbon dioxide.

• If we place lime water in the open air, it turns milky due to absorption of carbon dioxide from the air. 


• Water was shown by Cavendish, in the eighteenth century, to be a chemical compound.

• It consists of hydrogen and oxygen in the ratio of 2:1 by volume and 1:8 by mass.

Hence, when an electric current is passed through acidifi ed or alkaline water for every

one volume of oxygen two volumes of hydrogen evolve.

• Water can be prepared by combining oxygen and hydrogen with the help of an electric

current where for every one part of hydrogen, 8 parts of oxygen are required. Boiling

point of water is 100°C and freezing point is 0°C.

Hard and Soft Water

Hard Water: Does not produce lather with soap.

Soft Water: Produces lather with soap very easily.

Hardness of water is of two types:

1. Temporary hardness is due to the bicarbonates of calcium and magnesium. It can be

removed by (a) boiling or (b) addition of lime.

2. Permanent hardness is due to the sulphates and chlorides of calcium and

magnesium. It can be removed by (a) addition of washing soda or (b) distillation.

Rain Water: It is the purest form of water since it is condensed water vapour of the air. It

is soft water because it does not contain salts like bicarbonates, sulphates and chlorides

of calcium and magnesium.

River Water: By fl owing over the earth’s surface carries with it soluble minerals of earth

and becomes hard water and also contains several pollutants.

Important Gases

Oxygen: Is a colourless, odourless and tasteless gas, sparingly soluble in water and slightly

heavier than air. It does not burn itself but helps in burning of other substances. It is found

in abundance in the earth both in the free state and combined state with other elements.

• Oxygen can be prepared in a laboratory by heating potassium chlorate and manganese

dioxide together. It can also be obtained in small quantities by heating oxides or salts rich in

oxygen. Oxygen can be separated from the air by passing an electric current through water.

• It is essential for plant and animal respiration and for nearly all kinds of combustion.

 Atomic No. 8 Relative atomic mass: 15.999

 Melting point: –218.4°C Boiling point: –183.0°C

 Density at 0°C = 1.329 kg/m3 Valency: 2

Hydrogen: Is a colourless, highly fl ammable gaseous element, the lightest of all substances

known and in most abundant supply in the universe. In the free state it occurs in volcanic


• Hydrogen burns with a pale blue fl ame but does not help combustion and is slightly

soluble in water. It is used in the manufacture of vanaspati ghee, alcohol and ammonia.

• Hydrogen can he obtained from water, acids and alkalies. In a laboratory it is prepared

by the action of dilute sulphuric acid on commercial zinc.

 Atomic No. 1 Relative atomic mass: 1.008

 Melting point: –259.14°C Boiling point: –252.5°C

 Density: 0.08988 kg/m3 Valency: 1

Nitrogen: A colourless, tasteless and odourless gas constituting nearly four-fi fths of the air

by volume. It is an almost inert diatomic gas, neither combustible nor helping combustion.

Slightly soluble in water.

• In a laboratory it can be prepared by heating ammonium nitrite. On a large scale it can

be obtained from air. Air is liquefi ed fi rst and then evaporated, nitrogen evaporates

fi rst, leaving oxygen. Nitrogen is used to manufacture nitric acid, ammonia and


 Atomic No. 7 Relative atomic mass: 14,007

 Melting point: –209.86°C Boiling point: –195°C

 Valencies: 3 and 5

Carbon Dioxide: A colourless, odourless, incombustible gas formed during respiration,

combustion and organic decomposition and is heavier than air.

• Carbon dioxide is acidic and turns lime water milky. It is used in food refrigeration, carbonated beverages, fi re extinguishers, etc.  

• Carbon dioxide is prepared by the action of dilute acids on carbonates or by

fermentation of sugar. In a laboratory it can be prepared by treating marble pieces with dilute hydrochloric acid.



• Soaps are the alkali salts of higher fatty acids. Washing soap is, sodium salt of strearic

acid and toilet soap is potassium salt of oleic acid. These soaps contain a charged

COONa+ end and a hydrocarbon end CnH2n+1.

• The charged end has a tendency to interact with polar substances like water and fi bre,

while the hydrocarbon part interacts with non-polar material like oil.

Cleansing Action of Soaps: It is based on a surface phenomenon. Oil coats the surface of

objects (for example, fi bre) involving weak interactions between the polar fi bres and the non-

polar oil.

• When clothes are soaked with water containing soap then the polar end of the soap

orients towards oil.

• The stronger interaction between the charged end of soap and water overweighs the

weak interaction between the fi bre and oil. Thus the interfacial contact between the oil

(dirt etc.) and the fi bre (or any other object) is reduced and oil separates in the form of droplets. 


• Glass is a mixture of an alkali silicate with the silicate of a base, that is, silica, sodium

silicate (Na2SiO3) and calcium or lead silicate.

• The selected materials, that is, sand (silica), soda ash (sodium carbonate) and lime

stone (calcium carbonate) are mixed in the required proportion and broken pieces of

previously made glass known as ‘cullet’ are added.

• These help in easier fusion of the mixture. The mixture is heated up to a temperature

of 1400°C in a rotary furnace.

• When the mass is completely mixed and melted, the glass is made in various shapes

by blowing and moulding.


• Materials required to manufacture cement are calcium carbonate (limestone, chalk, etc.)

aluminium silicate (clay) and a small qantity of gypsum (CaSO4.2H2O).

• The best cement is Portland cement, the average composition of which is CaO (63%);

Fe2O3 (3%); MgO (1.5%); Akali (0.5%); SiO2 (21%); SO3 (1.5%); A12O3 (7%).

• The raw materials are fi rst crushed and mixed together and ground to a fi ne powder. The

powder is then fed in a kiln (Temperature: 1890 K). At this temperature calcium oxide

(from limestone) combines the aluminium silicate to form calcium silicate and aluminate.

The resultant mixture is mixed with 2–3% gypsum and ground to form cement.


• Coal originates from the remains of trees, bushes, ferns, mosses and other forms of

plant life that fl ourished in swamps and marshes millions of years ago.

• Important products are derived from coal by a process called pyrolysis—heating of

coal in the absence of air which produces coke (residue) and volatile matter such as

coal gas and a liquid known as coal tar.


Carbon Compounds

• Until 1828 scientists believed that organic compounds occur only in living organisms,

things that were or had been alive. Therefore, study of those compounds became known as organic chemistry.

This was based on the so-called vitalist theory, that is, to produce organic compounds,

vital energy is required.

• However, the vital force theory was disapproved when in 1828, the German chemist,

Friedrich Wohler, prepared an organic compound Urea in his laboratory by evaporating

a solution of inorganic compound ammonium cyanide:


 Ammonium cyanide Urea

 (inorganic compound) (organic compound)

• Therefore, now organic chemistry is the study of carbon compounds.

Organic and Inorganic Compounds

• Most organic compounds can be burned while most inorganic compounds cannot.

• Most organic compounds are gases, volatile liquids and solids, with relatively low

melting points and most inorganic compounds are solids with high melting points.

• While most organic compounds are insoluble in water, a great majority of inorganic compounds are soluble. 


• Found in abundance, carbon ranks twelfth among the elements in the earth’s crust but

in importance it ranks fi rst.

• It is a unique element which readily combines with itself to form large molecules of

carbon atoms linked in long chains (rings).

• In all there are more than a million such combinations.

Diff erent forms of Carbon: Diff erent forms of carbon are— (a) diamond; (b) graphite;

(c) charcoal; (d) lamp black; (e) coke; (f) gas carbon; (g) coal and (h) animal charcoal.

Allotropic forms of Carbon: When a substance exists in different crystalline

modifi cations the phenomenon is called allotropy and diff erent distinct forms of the

substance are called allotropes.

• Carbon shows allotropy because it exists in diff erent forms. There are two allotropic

forms of carbon, namely, (i) Diamond and (ii) Graphite.

• Coke, charcoal, lamp black, etc., were thought to be amorphous forms (without

defi nite shape) of carbon but it is now known that all the amorphous carbons contain

microcrystals of graphite.

• Though these allotropes of carbon have diff erent crystal structures and diff erent

physical properties, their chemical symbol is the same and show similar chemical

properties. Both diamond and graphite have symbol ‘C’.

• Both give off carbon dioxide when strongly heated in the presence of oxygen:

C (diamond) + O2 (gas) → CO2 (gas)

C (graphite) + O2 (gas) → CO2 (gas)

Diamond: Is the hardest substance found in natural form. Its name is derived from

the Greek word ‘adamas’ which means invincible or adamant. It is the purest form of

carbon. It does not allow heat or electricity to pass through. It is inert as it resists action

of chemicals but gives out CO2 when strongly burnt in air. It is insoluble in all solvents.

• Since 1955 diamonds are also prepared synthetically from carbon compounds at high

temperature and very high pressure.

• The transparent form of the diamond is used as gems while dark coloured diamonds

are used for making cutting-tools.

• The Koh-i-Noor is the world’s most precious and famous diamond mined in India

but was taken away by the British. The Cullinan found in 1905 in South Africa is the

largest diamond in the world weighing 570 grams and 2.850 carats.

Graphite: The name graphite is derived from the Greek word graphein that means

‘to write’. This suggests that this substance has been used to make lead pencils since ancient times. 

• Graphite is dark grey, an opaque solid with a soapy touch and has a metallic shine. It is

a good conductor of electricity and heat. It does not undergo any change when mixed

with acids or alkalies. However, when heated with nitric acid graphite acid is formed.

• Graphite is used as a lubricant in paints for making electrodes and lead pencils.

• Pure graphite is manufactured by heating coke in an electric furnace to a temperature

of about 2500°C in the absence of air.


• Is a mixture of hydrocarbons believed to have originated from bacterial decomposition

of animal and vegetable fats under high pressure and atmospheric temperature?

• It is converted into a variety of products by Fractional Distillation based on the

principle that lower hydrocarbons boil at a lower temperature than the higher ones.

Liquefied Petroleum Gas (LPG)

• Domestic gas also known as LPG or bottled gas or liquefi ed petroleum gas is a

by-product of petroleum refi ning and also obtained from natural gas. It is a mixture of

hydrocarbons such as propane, butane and pentane.

• These gases can be liquefi ed under moderate pressure at normal temperature. Because

of low boiling point (–44°C) these gases are stored under pressure to keep in a liquid

state in gas cylinders.

• Therefore cooking gas cylinders contain the mixture of these gases in liquid form.

Synthetic Rubber

• Produced by polymerization of certain hydrocarbons, namely, (i) Neoprene—a

polymer of chloroprene; (ii) BUNA-S—a polymer of styrene and butadiene and

(iii) BUNA-N—a polymer of butadiene and acrylonitrile.

• Rubber is made hard by vulcanization, a process of heating rubber with sulphur.

Synthetic Fibre

Nylon: was the fi rst synthetic fi bre made as a result of research begun in 1928. It is a

polyamide made by polymerizing adipic acid and hexamethylene diamine.

Terylene: Discovered in 1943. Produced from terephthalic acid and ethylene glycol.

Plastics: There are certain synthetic materials which are neither rubber nor fi ber but are

used as a substitute. These are called plastics.

• Plastics are also polymers. The raw material is basically a polymer of acetylene, the

common gas used for welding.

• The polymer is obtained by treating acetylene gas under pressure in presence of a

catalyst. The result is a long-chain molecule.


• A phenomenon of spontaneous disintegration, fi rst observed in certain naturally

occurring heavy elements like radium, actinium, uranium, thorium, etc., with the

emission of alpha, beta and gamma rays.

• It is the property of the nuclide to disintegrate in which a transformation takes place of

a relatively unstable nuclide to relatively stable nuclide accompanied with the emission

of particles or electromagnetic radiation.

• The nuclide that decays is said to be radioactive.

Discovery of Radioactivity: The phenomenon was accidentally discovered in 1896 by

French physicist Henry de Becquerel. He observed that uranium mineral gave off invisible

radiation. He termed this property of uranium radioactivity. Later Pierre and Madam

Curie showed similar phenomenon in other metals like poeonium, francium and radium.

Radioactive Emissions

Sub-atomic Particles (Radiation)

1. Alpha (α) particles: A positively charged helium atom which has very little

penetrating power. They can be absorbed by a sheet of paper or stopped by aluminum foil.

2. Beta (β) particles: A negatively charged light particle. Its penetrating power is

greater than that of alpha-ray.

Penetrating Particles (Radiation): Also called Gamma (γ) emission. These are

electromagnetic radiations of low wavelength, high frequency and high energy. Their

penetrating power is very great as they can pass through several centimeter of lead.


• X-rays are a form of penetrating electromagnetic radiation similar to light but of

shorter wavelength and capable of penetrating solids.

• X-rays are produced when cathode rays fall on anti-cathodes (a metal of high atomic

mass like tungsten).

X-ray Photographs: X-ray passes through considerable thickness of matter without being

entirely absorbed. although a fraction of the original radiation is always lost.

• Dense materials such as metal and bone, absorb X-rays more strongly than materials

such as wood or fl esh. Therefore, it is possible to produce X-ray photographs for use

in medical diagnosis.

Nuclear Reaction and Atomic Energy

• Nuclear Reaction: A nuclear reaction is one in which a nucleus bombarded with an

elementary particle (like neutron, proton etc.) or with another nucleus to produce

other products in a very short time span. The fi rst nuclear reaction was discovered by

Rutherford in 1919 when he bombarded nitrogen with alpha particles.

• Nuclear Fission: Nuclear fi ssion is the fragmentation of a large nucleus into two smaller

nuclei and the liberation of large amount of energy. In 1939 the German scientists

Otto Hahn and F. Steersman observed that when uranium was bombarded with slow

neutrons, then two smaller products were obtained with a tremendous amount of heat.

The splitting of uranium was called nuclear fi ssion

Types of Nuclear Fission:

1. Controlled Nuclear Fission: Carried out in nuclear reactors in which rate of fi ssion

reaction is reduced and energy produced can be used for constructive purposes;

2. Uncontrolled Nuclear Fission: In an atom bomb uncontrolled fi ssion takes place.

A very large amount of heat is produced and the process continues until the entire

amount of fi ssionable material is exhausted.

• First Atom Bomb: On 6 August 1945, an atom bomb was dropped on Hiroshima city in

Japan. The second bomb was dropped on Nagasaki, another city of Japan on 9 August

1945. The bomb was made of plutonium-239.

• Nuclear Fusion: It is a nuclear reaction in which lighter nuclei fuse to form a nucleus

of greater mass. In this reaction also an enormous amount of heat is produced. By

carrying on nuclear fusion under controlled conditions, the large amount of energy

could be made available for useful purpose.

• Atomic Energy (Nuclear Energy): Energy produced by nuclear fi ssion or nuclear

fusion is called nuclear energy or atomic energy. In nuclear reactions there is loss of

mass. This mass is converted into energy. It can be transformed into electrical and

mechanical energy which can be used for various peaceful purposes.


Beer’s Law

• States that in photo chemistry the proportion of light absorbed by a solution depends

on the thickness of the absorbing layer and on the concentration of the absorbing

substance in the solution.

Boyle’s Law

• States that the volume (V) of a given mass of gas at a constant temperature is inversely

proportional to its pressure (p), that is, pV = constant.

• This means that if a gas is compressed threefold its volume is reduced by two-thirds.

• Boyle (1627–90) was the fi rst to defi ne an element as a substance that cannot be broken

down into something simpler by a chemical process.

Charle’s Law

• States that under constant pressure the volume of a fi xed mass of gas varies directly with its absolute temperature. 

• The absolute temperature is that measured from absolute zero, about −273° on the

Celsius scale.

• In other words, the pressure of a gas increases by 1/273 of its volume at 0°C for every

1°C rise in temperature.

• In other words, if the pressure of a gas remains constant, the volume of a gas increases

by 1/273 of its volume at 0°C for every 1°C rise in temperature.

• Alternatively, at constant pressure the volume of a given ma ss of gas is directly

proportional to the absolute temperature.

• The principle was formulated by the French scientist, Jacques Alexandre Charles.

Faraday’s Law of Electrolysis

• States that (i) The amount of decomposition during electrolysis is proportional to

the quantity of current passed and (ii) For the same quantity of electricity passed

through diff erent solutions, the extent of decomposition is proportional to the chemical

equivalent of the element or group liberated.

• The law was formulated by an English chemist, Michael Faraday (1791–1867).

Gay-Lussac’s Law

• Law of Gaseous Volume: States that when gases combine chemically, the volumes of the

reactive gases and gaseous products are in simple proportion at the same temperature

and pressure. In other words, when gases combine they do so in volumes which are in a

simple ratio to each other and to that of the product, if it is also gaseous. For example,

One volume of nitrogen combines with three volumes of hydrogen to form two volumes of Ammonia. 

• Law of Thermal Expansion: It states that at constant pressure all gases expanded by the same amount for the same increase in temperature. These laws were formulated by a  

French chemist, Joseph Lois Gay-Lussac (1778–1850).

Hess’ Law

• States that the heat exchange in a chemical reaction is the same, no matter whether the

reaction takes place in one stage or more.

• The principle was formulated by a German chemist Henri Hess (1802–50).

Graham’s Law of Diffusion

• States that the rate at which two gases diff use is inversely proportional to their densities.

• It means that the lighter the gas, the faster it will diff use through any medium.

• The law was defi ned by a Scottish chemist, Thomas Graham (1805–60).

Henry’s Law

• States that the mass of a gas which is dissolved in a given volume of liquid at constant

temperature is directly proportional to the pressure of the gas.

• It applies to gases that do not react with the liquid (solvent).

• The principle was formulated in 1803 by the British chemist William Henry.

Lambert’s Law

• States that layers of equal thickness of homogeneous material, for example, coloured

filter), absorb equal proportion of light.

Raoult’s Law

• States that the lowering of the vapour pressure of a solvent by a solute (dissolved

substance) is proportional to the MOLE fraction of the solute, the proportion of solute

molecules to the total number of molecules, solute and solvent present.

• Since the lowering of vapour pressure causes an elevation of the boiling point and

a depression of the freezing point, it is used to determine the molecular mass of a solute. 

• The law is named after the French chemist, Francois Marie Raoult (1840–1901).

Law of Conservation of Mass and Matter

• Matter can neither be created nor destroyed.

• The sum total of mass or matter for a system always remains constant without any increase or decrease in quantity. 


• Bessemer Process: It is a method of converting pig iron to steel by blowing air through

the molten metals to oxidize impurities such as carbon, silicon, phosphorus and

manganese normally present in pig iron.

• Clemmensen Reduction: It is a process used to convert aldehydes and ketones to the

corresponding hydrocarbons by heating with amalgamated zinc and hydrochloric acid.

• Gattermann Reaction: It is a process used to convert an aromatic amine into the

corresponding halogen derivative through diazonium salt formation using copper as a catalyst.

Haber Process: An industrial process of producing ammonia by the reaction of

nitrogen with hydrogen in the presence of a catalyst.

• Kolbe Reaction: It is used for the preparation of saturated or unsaturated hydrocarbons

by the electrolysis of solutions of the alkali salts of aliphatic carboxylic acids.

• Solvay Process: It is a process of snaking sodium carbonate from calcium carbonate

and sodium chloride in large scale. The process involves heating of calcium carbonate

to give calcium oxide and carbon dioxide which is bubbled into a solution of sodium

chloride in ammonia. Sodium hydrogen carbonate is precipitated which on heating

gives sodium carbonate.

• Bayer Process: A process used to extract aluminium oxide Al2O3 or aluminia by

treating powdered bauxite with hot caustic soda solution under pressure. The process

was developed by German chemist, Karl Joseph Bayer in 1888.

• Bergius Process: A process for making lubricants and synthetic fuel for example,

petrol, from coal by heating a mixture of powdered coal and heavy oil or tar with

hydrogen under pressure in the presence of a catalyst (iron, tin or lead). The process was

developed by German chemist, Friedrich Bergius, who shared the 1931 Nobel Prize.

• Bosch Process: A process used to make industrial hydrogen by passing steam over

white-hot coke to produce water gas (a mixture of carbon monoxide and hydrogen)

which in the presence of a catalyst (a metal oxide) reacts with more steam to liberate

hydrogen and carbon dioxide. The process is named after the German chemist, Carl

Bosch (1874–1940).

• Down Process: It is a process of making sodium metal by electrolysis of molten

sodium chloride. The molten sodium and calcium formed at the cathode are separated.

• Frasch Process: It is used to extract sulphur from subterranean deposits in which

superheated water is forced down the deposits which melts the sulphur under the

ground. Molten sulphur is collected by forcing compressed air from another side. The

process was developed by German chemist, Herman Frasch in 1891.

• Hall-Heroult Process (Hall-Heroult): A process used to prepare aluminium by electrolysis

in which aluminia (aluminium oxide) is dissolved in cryolite (sodium aluminium fl uoride)

and electrolyzed. It was developed in 1885 in US by Charles Hall and in France by

P. T. Heroult.

• Parkes Process: A process used for extraction of silver traces from lead ore galena.

Molten zinc is added to molten galena and lead is separated leaving zinc-silver which

on heating distills off zinc freeing the silver.


• Brown-ring Test: It is used for chemical analysis of nitrates in which the solution to be

tested is mixed with iron sulphate solution in a test tube and concentrated H2SO4 (sulphuric

acid) is carefully poured along the side of the test tube. In nitrate containing substances a

brown ring is formed where the layer of acid touches the solution (FeNO)SO4.

• Flame Test: It is used to identify certain elements in which a clean platinum wire is

dipped into the mixture to be tested and the wire is heated using a busen fl ame. The

presence of certain elements can be detected by the change in the colour of fl ame. For

example, a brilliant orange-yellow will indicate sodium; crimson, strontium and apple green, barium.

• Beilstein’s Test: It is used for the detection of halogen in an organic compound in which

a clean copper wire is heated in an oxidizing fl ame till the fl ame is no longer green.

The wire is then dipped in a solution of the substance to be analyzed and heated again.

If Cl, Br or I is present the fl ame turns a bright green.

• Fehling’s Test: It is used to detect sugars and aldehydes in a solution. Equal amounts

of solution of copper sulphate (Fehling A) and sodium tartrate (Fehling B) are mixed

in a test tube, On boiling this with a given solution a red precipitate forms if sugar or

aldehyde is present.

• Kjedahl Method: It is used to measure nitrogen in an organic compound. The

compound is boiled with concentrated sulphuric acid and copper sulphate (catalyst) to

convert nitrogen to ammonium sulphate. An alkali is added to the mixture and boiled

to distill of ammonia which is passed into a standard acid solution and estimated by

titrating the solution.

• Molish’s Test: It is used to detect carbohydrates in a solution. The solution to be tested

is mixed with a small quantity of alcoholic alphanaphthol and concentrated sulphuric

acid is slowly poured down the side of the test tube. When the two liquids meet the

formation of a deep violet rings indicates presence of carbohydrate.

• Rast’s Method: It is used to determine molecular weight by measuring the depression

of freezing point of a camphor by a known weight of the solute.

• Schiff ’s Test: It is used to distinguish between aldehydes and ketones. An aqueous solution of rosaniline and sulphurous acid (Schiff ’s reagent) is used to test for the  

its original magenta colour. The aldehydes restore the colour immediately whereas ketones, restore the colour slowly.

presence of aldehydes, which oxidize the reduced form of the dye rosaniline back to

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