RESERVATION IN INDIA: AN OVERVIEW

Reservation In India

·        ” Reservation” in India means an affirmative action through which a proportion of seats are reserved in the public sector units, Union / State civil Services, Union/State governments departments, and in all public/private educational institutions (except in religious/linguistic minority educational institutions).

·        Reservation is provided to the socially and educationally backward classes, scheduled castes and scheduled tribes to have their ample representation in services and institutions.

·        SC’s & ST’s enjoy the reservation provision in Union & State legislatures.

·        Caste is the predominant factor used for reservation in India. The whole group to whom the benefits of reservation are available in India is collectively known as backward class. This backward class has 3 sub categories.

1.   Scheduled Castes

2.   Scheduled Tribes & other

3.   Backward classes

Schedules Castes & Scheduled Tribes

·        SCs & STs are groups of Indian Population explicitly recognized by the Indian Constitution. But the constitution does not contain a definition of SCs & STs.

·        In the period of British rule in India, this group was collectively referred as “Depressed Classes”.

·        The constitution empowers the President of India to draw up a list of Scheduled Castes as well as Scheduled Tribes in each state of India in consultation with the concerned Governors. These lists may be revised by Parliament (Art.341,342)

·        As per the census 2001, SCs & STs collectively constitute nearly 24.56% of the total population of India.

·        Scheduled Castes (also known as Dalits) constitute over16% & Scheduled Tribes (referred as Adivasis) constitute over 8% of India’s population.

Other Backward Caste (OBCs)

·        The constitution of India also contains provision for Backward classes other than SCs & STs.

·        Article 340 makes it obligatory for the Government to promote the welfare of OBCs and empowers the President to appoint a commission to investigate the conditions of Backward classes.

·        Kalelkar commission (report 1955) and Mandal Commission (report 1980) were appointed under Art.340

·        The Kalelkar Report identified 2399 backward castes and Mandal Report estimated the proportion of OBC’s population in Indian Population at 52%.

·        National Sample survey put this figure at 32%. So neither the definition nor the proportion of other backward classes is available.

Purpose of Reservation:

·        The primary purpose of reservation is upliftment of the depressed classes and increasing social diversity in campuses and work places.

·        Those identifiable groups which are under represented in comparison to their proportion in population are provided an opportunity to have a seat in services or institution through reservation.

·        Although there are many criteria for judging under representation, such as gender, domicile and income etc, caste is the most used criterion.

·        The underlying theory is that the under-representation of identifiable groups is a legacy of the Indian Caste system.

·        Thus a cherished purpose of reservation is to incorporate in the main stream, those castes which were denied all opportunities of advancement and remained perpetually downtrodden under caste system.

History of Reservation in India

·       In ancient India, reservation may be said to have existed in form of strict division of labour on caste lines. Bur such type of division was more or less, a negative reservation, prohibiting lower castes to perform higher jobs.

·       In pre-independence modern India, ‘reservation’ was used as a major tactic under the strategy of “Divide and Rule”. The “Communal representation” in legislatures and civil posts laid the tradition of political use of reservation, which seems to be still continuing.

·        The demand for reservation of government job was made as early as 1891 by the natives of Princely State of Travancore. Till 1901, reservations were in force in Kolhapur, Baroda & Mysore.

·        Morley-Minto Reforms, 1909 and Montague-Chelmsford Reforms.1919 provided for communal reservation. The Poona Pact, 1935, reserved electoral constituencies for depressed classes.

·        The constitution of India as framed in 1949, contained a scope for reservation, for next 10 years (which has been subsequently extended for every 10 years).

·        In the post-independence era, the reservation issue turned furious when the Mandal commission’s recommendation was implemented in 1990 hiking the quotas from 22.5% to 49.5%.

·        In 1991, Central Government introduced 10% separate reservation for Poor among Forward Castes.

·        In 1955, 77^th constitutional amendment inserted Article 16(4)(A) permitting reservations in ‘Promotion” to SCs & STs.

·        In 1998, Central government conducted a nationwide survey to estimate economic ad educational status of various social groups. The National Sample Survey estimated the proportion of backward population in India at 32%.

·        In 2005, 93^rd constitutional amendment provided the reservations to OBCs, SCs & STs in private educational institutions.

·        In 2006, reservation was provided to OBCs in Central government educational institutes hiking the total quota up to 49.5%.

·        In April 2008, the Supreme Court upheld he governments move for initiating 27% OBC quota in government- funded institutions.

Constitutional Premise

·        Article 338,338-A & 340 of Indian constitution contains explicit provisions, safeguarding the interests of SCs, STs& OBCs.

·        Interestingly, Articles 14, 15 & 16 collectively enshrine the principle of equality and absence of discrimination and they do carry the implicit provisions for reservation.

·        The Article14 is generally stated and ensures that everyone is equal in the eyes of law.

·        Article 15 prohibits the discrimination against any citizen in any matter at the disposal of the state on any of the specified grounds.

·        Article 16 is a safe guard against discrimination in employment under State.

·        Article 15(3) says that nothing shall prevent the state from making any special provision for women and children.

·        Article 15(4) empowers the State to make special provisions for the SCs, STs and socially/educationally backward classes.

·        The Article 16(3) allows the Parliament to provide for a residence or domicile based reservation in services.

·        And then, comes the masterstroke for reservation i.e., Article 16(4). This article expressly allows the state to reserve any post or appointment in favour of any backward class of citizens.

    Present scenario:

·        The most important guidelines regarding the quotas of reservation and other related matters were issued by supreme court in Indra Sawhney Case,1992 (Popularly known as Mandal commission Case),such as

·        The backwardness contemplated in Article 16(4) is mainly social backwardness.

·        The reservation should not exceed 50% appointments of each year.

·        ‘Creamy layer” must not be benefited through reservation.

·        Identification of backward classes is subject to judicial review.

Keeping in mind the above guidelines, Union government maintains a total 49.5% quota of reservation in services and institutions. The break up is as follows.

        Schedule Castes-15%

        Scheduled Tribes -7.5%

        Other Backward castes -27%

In case of States, the picture is not as vivid as at center. Different States provide for reservation differently, settling their local equations. Some states, to satisfy local demands, are exceeding the 50% limit fixed by Supreme Court, like Tamil Nadu (69%) and  Rajasthan(68%).

  

General studies(Chemistry)

Common Name	Chemical Name
Grain alcohol	ethyl alcohol
Wood Alcohol	methyl alcohol
alum	aluminum potassium sulfate
alumina	aluminum oxide
aqua regia	Nitro hydrochloric acid
aspirin	acetylsalicylic acid
baking soda	sodium bicarbonate
bleaching powder	chlorinated lime
blue vitriol	copper sulfate
brimstone	sulfur
carbolic acid	phenol
carbonic acid gas	carbon dioxide
epsom salts	gypsum
hypo (photography)	sodium thio sulfate solution
gypsum	natural calcium sulfate
lime	calcium oxide
lime, slaked	calcium hydroxide
limewater	aqueous solution of calcium hydroxide
lunar caustic	silver nitrate
magnesia	magnesium oxide
mercury oxide, black	mercurous oxide
methanol	methyl alcohol
methylated spirits	methyl alcohol
pearl ash	potassium carbonate

·         Transuranium elements have not been found in nature and can only be produced artificially (having atomic numbers higher than 92).

·         Temporary hardness of water is due to the presence of bicarbonates of calcium and magnesium in water. Whereas the permanent hardness is due to the presence of Calcium Sulphate , which can be eliminated by the use of Zeolites i.e large group of minerals composed of hydrated aluminum silicates of alkali metals and alkaline earth metals such as stilbite, chabazite, natrolite, and analcime

·         The gas used in balloons is helium

·         A mixture of potassium chlorate and manganese dioxide is known as oxygen mixture.

·         Gobar gas is obtained by decomposition of vegetable matter and animal dung.

·         L.P.G (liquefied petroleum gas) consists of mainly propane and butane.

·         Natural gas is composed primarily of methane and other light hydrocarbons.

·         Carbon Dating, method for determining the approximate age of ancient objects by measuring the amount of carbon 14 they contain.

·         Ethylene gas is used for artificial fruit ripening

·         Sodium and potassium react vigorously with cold water so it is preserved under kerosene while phosphorus is spontaneously inflammable in air so preserved  under water.

·         Nitrous oxide is called laughing gas, in mild doses it is used as anesthetic

·         Haber process is used to manufacture ammonia in which nitrogen and hydrogen are made to combine in the ratio 1:3 at high pressures of 200-900 atmospheres

·         Nitric acid is used as fertilizers and explosives

·         Tri-nitro toluene and nitro glycerene are common explosives

·         A mixture of 2,4,6 tri nitro toluene and ammonium nitrate is called amatol and is used as a blasting material

·         Nessler’s reagent “It is used as test for ammonia and ammonium salts in which it produces an yellow colour or brown precipitate is obtained.

·         Arc process or birkeland –eyde process is an important process for the manufacture of nitric acid, evolved during first world war (1914-1918) by German.

·         Smelling salt is ammonium carbonate

·         Compounds of nitrogen with metals are called nitrides

·         Sal ammoniac is ammonium chloride.

·         Battery electrolyte consists of a mixture of ammonium chloride and zinc chloride made into a paste.

·         Potassium nitrate or Nitre or Indian salt petre is used as Gun powder. Saltpeter is of commercial importance as a fertilizer, in the manufacture of glass, as a food preservative, and in some medicines as a diuretic. Saltpeter was once used in gunpowder and is now found in explosives, fireworks, and matches. In addition, this substance is employed in fluxes used in metallurgy. It is important as a source of nitrogen in the manufacture of nitrogen- containing compounds, particularly nitric acid, and as an oxidizing agent in many industrial chemical processes.

·         Chile saltpeter, or soda niter, is composed of sodium nitrate, NaNO3. It occurs over vast areas in South America, particularly in Chile.

·         Iron loses its property of liberating hydrogen from dilute acid and displacing other metals, when it is kept in contact with concentrated Nitric acid for some time . It is called passivity.

·         The common harmful gases are carbon monoxide from internal combustion engine, sulphur dioxide from industries and oxides of nitrogen from vehicles.

·         Dust particles from the cement factories are made to settle down by electrophoresis i.e. by huge electrodes on the top of the building carrying nearly a million volts of electricity.

·         Essential plant nutrients are Nitrogen, Phosphorus and Potassium (NPK)

·         Nitrogen is essential for rapid growth and increased yield of crops. Deficiency is indicated by yellowing of leaves. Phosphorous promote early growth and maturity of plants. Deficiency is indicated by purpling of leaves, ripening and fruiting is poor. Potassium develops a healthy root system. It deficiency is indicated by white, yellow and reddish brown spots on the leaves.

·         In the purification of water for drinking purposes, the suspended impurities such as clay and fine particles of sand are first coagulated by addition of the required quantity of aluminium sulphate which is known as filter alum

·         The paste applied to the side of a match box is a mixture of Phosphorous Tri sulphide, glass powder and sand to cause frictions and glue. The match head contains a readily combustible substance like antimony trisulphide, an oxidizing agent like potassium chlorate which maintains the combustion and a binding material like glue.

·         Marble is calcium carbonate

·         Vinegar is acetic acid

·         Methylated spirit is a mixture of methyl alcohol and ethyl alcohol

·         Urea is the first organic compound prepared in the laboratory

·         Carbonic acid is soda water

·         Mercaptans “leakage in L.P.G cylinders is easily detected.

·         Hydrazine is used to propel rockets

·         Coke is obtained by healthy wood out of contact with air

·         1 Carat = 200 mg

·         Terylene and nylon are synthetic fibres produced by a process of polymerization. Terylene is a polyester and Nylon a polymide.

·         Pyrene is carbon tetrachloride specially used to extinguish electrical fires.

·         Tincture iodine is a solution of iodine in alcohol.

·         Soft water lather easily with soap.

·         Nickel is used in conversion of oil into solid fat.

·         The presence of dust particles in the air serves as a nucleaus to condense water vapour resulting in rain.

·         The substance that is found abundly in seawater is sodium chloride.

·         The metal, which reacts violently with cold water, is potassium

·         Pyrene is the commercial name for carbon tetrachloride

·         Glaubers salt is Na₂SO₄ 10H₂0

·         Hypo is sodium thiosulphate extremely soluble in water

·         Hygroscopic substance is one which absorbs moisture from the air but does not turn into liqid. E.g. ethyl alcohol.

·         Coal gas is the product of destructive distillation of coal i.e. heating coal out of contact of air

·         Calgon is the trade name given to a complex salt sodium hexametaphosphate which removes calcium and magnesium present in the hard water thus making
 soft and fit for use in boilers.

·         The domestic cooking gas consists of mostly liquefied butane and isobutene

·         Manometer is the instrument for measuring the pressure of liquids and gases.

·         Rust is hydrated ferric oxide

·         The chief component of pearl is ferric component

·         The fibrous form of several minerals and hydrous silicates of magnesium. The name may also be applied to the fibrous forms of calcium and iron.

·         An ion is an electrically charged atom or molecule. Negatively charged ions are known as anions (which are attracted to anodes) while positively charged ions are known as cations (which are attracted to cathodes

Distillation
Distillation is a technique for separating components of a mixture on the basis of differing boiling points. The mixture is heated, vaporizing some of the components. The vapor is collected and condensed to isolate the components with the lowest boiling points.

Ethanol. (CH₃CH₂OH) ethyl alcohol; grain alcohol
A colorless, flammable liquid produced by fermentation of sugars. Ethanol is the alcohol found in alcoholic beverages. Ethyl alcohol is used as a solvent, extractant, antifreeze, intermediate in the synthesis of innumerable organic chemicals and as a fuel and gasoline additive

Emulsion
A colloid formed from tiny liquid droplets suspended in another, immiscible liquid. Milk is an example of an emulsion

Fractional distillation
A technique for separation of liquid mixtures by distillation that uses a tower attached to a flask containing the mixture to perform multiple distillations. Vapor moving up the column condenses on packing material inside the column, trickles down the column, and again vaporises. The more volatile component can then be drawn off at the top of the component, while the less volatile component remains at the bottom.

Ketone.
An organic compound that contains a carbonyl group. For example, methyl ethyl ketone is CH³COCH²CH³ is used in some adhesives.

Efflorescent
Efflorescent substances lose water of crystallization to the air. The loss of water changes the crystal structure, often producing a powdery crust. The thermodynamic requirement for efflorescence is that the partial pressure of water vapor at the surface of the solid (its dissociation pressure) exceed the partial pressure of water vapor in the air. A typical efflorescent substance is Glaubers salt, Na²SO⁴ · 10H²O. The spontaneous loss of water normally requires that the crystal structure be rearranged, and consequently, efflorescent salts usually go to microcrystalline powders when they lose their water of hydration.

Ester

An ester is a compound formed from an acid and an alcohol. In esters of carboxylic acids, the -COOH group and the -OH group lose water and become a -COO- linkage

Gel
A gel is a sol in which the solid particles fuse or entangle to produce a rigid or semi rigid mixture. For example, gelatin dissolved in water produces a sol of protein molecules. When the gelatin is cooked, the protein chains entangle and crosslink, forming a gel which is a mesh of solid protein with trapped pockets of liquid inside. Fruit jellies are also gels

Foam
A colloid in which bubbles of gas are suspended in a solid or liquid. Aerogel (solid smoke) and Styrafoam are examples of solid foams; whipped cream is an example of a liquid foam

Reverse osmosis
Solvent molecules flow spontaneously from a dilute solution through a semi permeable membrane to a more concentrated solution (osmosis). In reverse osmosis, pressure is applied to the more concentrated solution to force the flow of solvent to go from more concentrated to more dilute solution. Reverse osmosis is used to produce fresh water from sea water.

Isomers
Isomers have identical molecular formulas but different structural formulas

Hygroscopic
Able to absorb moisture from air. For example, sodium hydroxide pellets are so hygroscopic that they dissolve in the water they absorb from the air.

Hydrazine.
A colorless, fuming, corrosive liquid that is a powerful reducing agent. It is used in jet and rocket fuels, and as an intermediate in the manufacture of agricultural, textile, photographic, and industrial chemicals.

Endothermic
A process that absorbs heat. The enthalpy change for an endothermic process has a positive sign. Some examples of endothermic processes are
Cooking food, melting of ice, De pressurising a pressure can
The mixing of barium hydroxide and ammonium thio cyanate causes a powerful endothermic reaction that causes the products to become so cold that the moisture from the air forms a layer of frost on the outer surface of the beaker.
Endothermic substances, both natural, e.g. gypsum, and synthetic, e.g. resin-based intumescents, are popular for use in heat shielding, ablation, materials in space physics, fireproofing, e.g. fire-resistive coatings for LPG vessels, and compartmentalisation of fire in buildings, which is the cornerstone of passive fire protection. Typically, the technological basis is the conversion of hydrates, or chemically bound water into vapour, or steam.

Exothermic
A process that releases heat. The enthalpy change for an exothermic process is negative. Examples of exothermic processes are

·         combustion reactions, freezing of water, respiration and neutralization reactions .

·         Adding concentrated acid to water

·         Adding water to anhydrous copper(II) sulfate

·         The reaction taking place with Thermite(fire-hazardous mixture of ferric oxide and powdered aluminum; upon ignition by a magnesium ribbon, it reaches a temperature of 4000°F (2200°C), sufficient to soften steel; used for industrial purposes or as an incendiary bomb.

·         Reactions taking place in a self-heating can based on lime and aluminum.

Sol
A colloid with solid particles suspended in a liquid. Examples are protoplasm, starch in water, and gels.

Tyndall effect
Light passing through a colloid is scattered by suspended particles. The light beam becomes clearly visible; this phenomenon is called the Tyndall effect. For example, car headlight beams can be seen in fog, but the beams are invisible in clear air.

Aerosol
A colloid in which solid particles or liquid droplets are suspended in a gas. Smoke is an example of a solid aerosol; fog is an example of a liquid aerosol.

Abrasive
A very hard, brittle, heat-resistant substance that is used to grind the edges or rough surfaces of an object. boron carbide, diamond, and corundum are abrasives.

Acidulant
A substance added to food or beverages to lower pH and to impart a tart, acid taste. Phosphoric acid is an acidulant added to cola drinks.

Activated charcoal
A porous form of carbon that acts as a powerful adsorbent , used to decolorize liquids, recover solvents, and remove toxins from water and air.

Alkaloid
A class of bitter-tasting, basic organic compounds with nitrogen-containing rings. Alkaloids often have powerful effects on living things. Examples are cocaine, nicotine, strychnine, caffeine, and morphine

Allotrope
Some elements occur in several distinct forms called allotropes. Allotropes have different chemical and physical properties. For example, graphite and diamond are allotropes of carbon.

Antichlor
A chemical compound that reacts with chlorine-based bleaches to stop the bleaching. Thiosulfate compounds are antichlors.

Antioxidant
Antioxidants are compounds that slow oxidation processes that degrade foods, fuels, rubber, plastic, and other materials. Antioxidants like butylated hydroxyanisole (BHA) are added to food to prevent fats from becoming rancid and to minimize decomposition of vitamins and essential fatty acids; they work by scavenging destructive free radicals from the food.

Free radical
A free radical is a molecule with an odd number of electrons. Free radicals do not have a completed octet and often undergo vigorous redox reactions. Free radicals produced within cells can react with membranes, enzymes, and genetic material, damaging or even killing the cell. Free radicals have been implicated in a number of degenerative conditions, from natural aging to Alzheimers disease

Avogadro number
It is formally defined to be the number of carbon-12 atoms in 12 grams (0.012 kg) of unbound carbon-12 in its rest-energy electronic state. The number of particles in one mole, equal to 6.02214199 × 10²³ mol-1 (± 0.00000047).

Colloid
A colloid is a heterogeneous mixture composed of tiny particles suspended in another material. The particles are larger than molecules but less than 1 µm in diameter. Particles this small do not settle out and pass right through filter paper. Milk is an example of a colloid. The particles can be solid, tiny droplets of liquid, or tiny bubbles of gas; the suspending medium can be a solid, liquid, or gas (although gas-gas colloids are not possible).

Carotene.
Carotene is an unsaturated hydrocarbon pigment found in many plants It is responsible for the orange colour of the carrot. Carotene is the basic building block of vitamin A.

Caffeine
A substance found in tea, coffee, and cola that acts as a stimulant. It is extremely soluble in supercritical fluid carbon dioxide and somewhat soluble in water; aqueous solutions of caffeine quickly break down.

Buffer
A solution that can maintain its pH value with little change when acids or bases are added to it. Buffer solutions are usually prepared as mixtures of a weak acid with its own salt or mixtures of salts of weak acids. For example, a 50:50 mixture of 1 M acetic acid and 1 M sodium acetate buffers pH around 4.7.

Diamond
A crystalline form of carbon, made of a network of covalent, tetrahedrally bound carbon atoms.

Deliquescent
Deliquescent compounds absorb so much moisture from the air that they dissolve. Examples are calcium chloride and sodium hydroxide

Dry cell or Leclanché cell
A electrolytic cell that uses a moist paste rather than a liquid as an electrolyte. Flashlight batteries are dry cells with a zinc cup for an anode, a carbon rod for a cathode, and a paste made of powdered carbon, NH₄Cl, ZnCl₂, and MnO₂ for an electrolyte.

AlloysAn alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal. Alloys are usually designed to have properties that are more desirable than those of their components. For instance, steel is stronger than iron, one of its main elements, and brass is more durable than copper, but more attractive than zinc.

Some Common Alloys:

Duraluminium	Aluminium 95%,copper 4%, magnesium (0.5%-“1%), and manganese (less than 1%).
Gun Metal	Copper 90%, Tin 10%
Steel	Iron 99 % , Carbon 1%
Stainless Steel	Iron with 0.1-2.1% carbon upto 27% chromium or 20% tunsten or 15% Nickal
Petwar	Tin,Antimony & Copper
Bronze	Copper, Tin and Zinc
German Silver	Copper,Zinc and Nickel
Electrum	Gold & Silver
18 carat Gold	Gold 75%, Silver & copper 25%
Dentist Amalgam	70% Mercury 30% Copper
Yellow Brass	Copper 67% Zinc 33%
Spiegeleisen	Iron , 15% manganese and carbon and silicon
Brass	Copper & 38% Zinc
Nichrome	Nickel & Chromium
Plumbers Solder	Lead and tin
Mu Metal	77% nickel, 15% iron, plus copper and molybdenum
An amalgam	refers to alloys of mercury.

Metals
Metals have certain characteristic physical properties: they are usually shiny (they have "lustre"), have a high density, are ductile and malleable, usually have a high melting point, are usually hard, and conduct electricity and heat. These properties are mainly because each atom exerts only a loose hold on its outermost electrons (valence electrons); On the periodic table, a diagonal line drawn from boron (B) to polonium (Po) separates the metals from the nonmetals. Most metals are grayish in color, but bismuth is pinkish, copper is red, and gold is yellow. Some metals display more than one colour, a phenomenon called pleochroism.

Ores
An ore is a mineral containing a metal as a proportion of its content. Usually, it is used in the context of a mineral from which it is economical to extract its metallic component. Ores are mined.

Substance	Important Ores
Aluminium	Bauxite Al2O3
Antimony	Stibnite Sb2S3
Beryllium	Beryl , Crysoberyl
Calcium	Lime stone, Marble, Chalk, Gypsum, Alabaster , Flurosper
Chromium	Chromite (Feo Cr2 O3)
Cobalt	Smaltite
Copper	Cuprite (Cu2O), Bornite
Iron	Hematite Fe2O3, Magnatite (Fe3O4)
Lead	Galena (Pbs), Masicot, Serusite
Magnicium	Magnesite, Dolomite, Carnallite
Manganese	Pyrolusite, Hausmannite
Mercury	Cinnabar
Molybdenum	Molybdenite & wulfenite
Nickel	Pantilandite and Gargnierite
Phosphorous	Phosphorite Apatite, Chlorapatite
Potassium	Carnelite , Saltpetre (KNO3)
Silver	Argentite(AgS2)
Sodium	Rock Salt( Nacl) Chile Saltpetre (NaNO3)
Sulphur	Galena, Copper Pyrites & Iron Pyrites
Tin	Cassiterite, Tin stone
Titanium	Rutile (TiO2), Ilmenite
Uranium	Pitchblende (UO2)
Zinc	Zinc Blends, Calamine

There are 3 types of process are employed for the metal extraction. They are Mechanical, Chemical and Electrical.
Some important processes are:

a) Gravity separation:

The crushed ore are suspended either in water or an air blast, the heavier metal or metallic mineral particles fall to the bottom of the processing chamber, and the lighter gangue is blown or washed away. Gold and magnetite are separated in this way.

b) Flotation: In this method, finely ground ore is mixed with a liquid. The metal or metallic mineral floats while the gangue sinks

c) Magnetic separation: Metals that have magnetic properties are concentrated by means of electromagnets that attract the metal but do not attract the gangue e.g. magnetite

d) Smelting: the ore is heated with a reducing agent and a flux to a high temperature. The reducing agent combines with the oxygen in a metallic oxide, leaving pure metal; and the flux combines with the gangue to form a slag that is liquid at the smelting temperature and thus can be skimmed off or poured away from the metal. The production of pig iron in blast furnaces is an example of smelting and the process is also used to extract copper, lead, nickel, and many other metals from their ores.

e) Amalgamation is a metallurgical process that utilizes mercury to dissolve silver or gold to form an amalgam. This process has been largely supplanted by the cyanide process, in which gold or silver is dissolved in solutions of sodium or potassium cyanide.

f) Electrolysis: In this process, the metal is deposited at the cathode from aqueous solutions or in an electrolytic furnace. Copper, nickel, zinc, silver, and gold are several examples of metals that are refined by deposition from aqueous solutions. Aluminium, barium, calcium, magnesium, beryllium, potassium, and sodium are metals that are processed in electrolytic furnaces.

Some interesting points

Osmium and iridium (specific gravity 22.6) are the most dense metals, and lithium (specific gravity 0.53) is the least dense. Bismuth has the lowest electrical conductivity of the metallic elements, and silver the highest at ordinary temperatures. Gallium, mercury, cesium, and rubidium are the only metal elements that melt near room temperature

Metalloids

A group of elements called metalloids, intermediate in properties between the metals and the nonmetals, are sometimes considered a separate class.

They have properties intermediate between those of metals and nonmetals. most common is that metalloids are usually semiconductors rather than conductors.

They are boron (B) silicon (Si) germanium (Ge) arsenic (As) antimony (Sb) tellurium (Te) Polonium (Po)

Non metal
A non metal is a substance that conducts heat and electricity poorly, is brittle or waxy or gaseous, and cannot be hammered into sheets or drawn into wire. Non metals gain electrons easily to form anions . About 20% of the known chemical elements are non metals. The oxides of nonmetals are acidic.

The nonmetals are, in order of atomic number:

hydrogen (H) carbon (C) nitrogen (N) oxygen (O) fluorine (F) phosphorus (P) sulfur (S) chlorine (Cl) selenium (Se) bromine (Br) iodine (I) astatine (At)

Alkali metals
Alkali Metals, series of six chemical elements in group 1 (or Ia) of the periodic table They are soft compared to other metals, have low melting points, and are so reactive that they are never found in nature uncombined with other elements. They are powerful reducing agents. The alkali metals are, in order of increasing atomic number, lithium, sodium, potassium, rubidium, cesium, and francium. Francium exists only in a radioactive form.

Alkaline Earth Metals

It is a series of six chemical elements in group 2 (or II A) of the periodic table. Although rather brittle, the alkaline earth metals are malleable, conduct electricity and when heated, burn readily in air. The alkaline earth metals are, in order of increasing atomic number, beryllium, magnesium, calcium, strontium, barium, and radium. Their oxides are called alkaline earths.

Compound
Compound is a substance formed from two or more elements, with a fixed ratio determining the composition. For example, water is a compound made out of hydrogen and oxygen in the ratio of two to one.

Mixture is the product of a mechanical blending or mixing of chemical substances like elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup. While there are no chemical changes in a mixture, physical properties of a mixture, such as its melting point, may differ from those of its components. Mixtures can usually be separated by mechanical means.

There are different types of Compounds are Acids, Bases, Salts, Oxides and organic compounds.

 

Acids

An acid (represented by the generic formula AH) is typically a water-soluble, sour-tasting chemical compound. An acid always has a pH of less than 7 and turns litmus red. It is a molecule or ion that contains hydrogen or that is able to give up a proton to a base, or accept an unshared pair of electrons from a base. An acid reacts with a base in a neutralization reaction to form a salt. Acids are electrolytes and react violently with metals to release hydrogen.

Acid	Remarks
ascetic acid	vinegar
amino acid	basis of protein
ascorbic acid	Vitamin C
carbolic acid/phenol	disinfectant
citric acid	citrus fruits
nitrohydrochloric acid(aqua regia)	dissolving gold and platinum
RNA/ ribonucleic acid	essential for protein synthesis
sulphuric acid	corrosive acid, wide applications
tartaric acid	used in baking powder
carbonic acid	carbonated beverages
DNA/ deoxyribonucleic acid	basis of chromosomes, so genetic transmission
formic acid	ants
lactic acid	sour milk
malic acid	unripe apples
nitric acid/aqua fortis	used in explosives and rocket fuels
prussic acid/ hydrocynic acid	poison
salicylic acid	basis of aspirin
tannic acid/tannin	found in tea
uric acid	in large amounts in the urine of birds and reptiles
oxalic acid	spinach

Bases

A base is a chemical compound that will neutralize an acid and form a salt + water. Bases are typically water-soluble, bitter tasting, turns litmus blue and always have a pH greater than 7 in solution. A base is able to take up a proton from an acid or able to give up an unshared pair of electrons to an acid. e.g. baking soda , sodium carbonate etc.

pH is a measure of effective concentration of hydrogen ions in a solution.

Litmus: A mixture of pigments extracted from certain lichens that turns blue in basic solution and red in acidic solution.

Salt

a salt is a neutral compound composed of cations bound to anions. They are typically the product of a chemical reaction between; base and an acid, forming a salt + water, or metal and an acid, forming a salt + hydrogen, or an acid forming oxide and a base forming oxide, forming a salt.

A cation is a positively charged ion. Metals typically form cations where as anions are negatively charged ion.

Organic compound

These contain carbon chemically bound to hydrogen. They often contain other elements (particularly O, N, halogens, or S). Organic compounds were once thought to be produced only by living things.

Elements
Elements are substances that cannot be decomposed or broken into more elementary substances by ordinary chemical means. Hydrogen, oxygen, chlorine, sodium, and iron are examples of elements. Ninety two elements are known to occur in nature, and 22 more have been made artificially. Elements having atomic number greater than 92 are Transuranium elements.

Some Common Elements and their applications

Air is a mixture of gases ; these gases consist primarily of the elements nitrogen, oxygen, argon, and smaller amounts of hydrogen, carbon dioxide, water vapor, helium, neon, krypton, xenon, and others.

Nitrogen
Nitrogen is the most abundant constituent in the atmosphere composes about four-fifths(78.03) percent by volume of the atmosphere. It is inert and serves as a moderate supporter of combustion. Nitrogen fixation is a process by which certain bacteria in the soil convert atmospheric nitrogen as nitrate that can be absorbed by plants . Nitrous oxide is known as laughing gas. Mixed with oxygen, nitrous oxide is used as an anesthetic for some types of surgery. Liquid nitrogen is used as coolant in cryogenics. The element occurs in the combined state in minerals, of which saltpetre (KNO₃) and chile saltpetre ( NaNO³) are commercially important products.

Oxygen
Oxygen is the most abundant element in the earth. It was discovered by Joseph priestly. Oxygen composes 21 percent by volume. It is used in high-temperature welding torches, administered to patients whose breathing is impaired and oxygen-enriched air is used in open-hearth furnaces for steel manufacture.

Most of the oxygen produced is used to make a mixture of carbon monoxide and hydrogen called synthesis gas, used for the synthesis of methanol and ammonia. High-purity oxygen is used also in the metal-fabrication industries; in liquid form it is of great importance as a propellant for guided missiles and rockets.

Argon
Argon is the third most prevalent gas in the earth’s atmosphere. Argon is also used in one type of neon lamp giving blue light whereas pure neon gives a red light. It is preferred because it requires a lower voltage than neon.

Hydrogen
Hydrogen exits as a gas at room temperature and is highly flammable. When hydrogen gas burns in air it forms water. In stars, hydrogen nuclei combine with each other in nuclear reactions to form helium atoms. The isotopes of Hydrogen are Deuterium and tritium. Researches have been conducting to use hydrogen as fuel for automobiles, refrigerators and airplanes. Spacecrafts use hydrogen as fuel that reacts with fluorine or oxygen. Nuclear plants use D2O as a moderator.

Carbon dioxide

Carbon dioxide does not burn and support ordinary combustion; it is used in fire extinguishers. Solid carbon dioxide is known as Dry ice widely used as refrigerant. The presence of carbon dioxide in the blood stimulates breathing. For this reason, CO₂ is added to the oxygen or ordinary air in artificial respiration and to the gases used in anaesthesia.

Inert gas
An Inert gas is a non-reactive gas . In order of increasing atomic weight are helium, neon, argon, krypton, xenon and radon. Liquefied noble gases, particularly xenon, are employed as solvents in infrared spectroscopy because they are transparent to infrared radiation and therefore do not obscure the spectra of the dissolved substances.

Methane
Methane also know as marsh gas, gas composed of carbon and hydrogen with formula CH₄, the first member of the paraffin or alkane series of hydrocarbons. It is lighter than air, colorless, odorless, and flammable. It occurs in natural gas, as firedamp in coal mines, as a by-product of petroleum refining, and as a product of decomposition of matter in swamps. It is a major component in the atmosphere of the outer planets, Jupiter, Saturn, Uranus, and Neptune.

Iron
Iron is a metal extracted from iron ore, and is hardly ever found in the free (elemental) state. In order to obtain elemental iron, the impurities must be removed by chemical reduction in blast furnace. Depending upon the carbon content Iron can be classified into

·         Pig Iron (4%-5%)

·         Cast iron(2-3.5%)

·         carbon steel(0.5-1.5%)

·         Wrought Iron( < 0.5%).

The Structure of Atoms:
The nucleus (atomic nucleus) is the center of an atom. It is composed of one or more protons and usually some neutrons as well. The simplest atom of all, hydrogen, has one particle—called a proton—in its nucleus.

Proton is a subatomic particle with a positive fundamental electric charge of 1.6 × 10^-19 coulomb and a mass of 938 MeV (1.6726231 × 10^-27 kg, or about 1800 times the mass of an electron).

Neutron is a subatomic particle with no net electric charge and a mass of 940 MeV (very slightly more than a proton). Its spin is 1/2. The nucleus of most atoms (all except the most common isotope of Hydrogen, which consists of a single proton only) consists of protons and neutrons. Outside the nucleus, neutrons are unstable and have a half-life of about 15 minutes, decaying by emitting an electron and antineutrino to become a proton.

Electron (also called negatron, commonly represented as e−) is a subatomic particle which carries a negative charge. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. The electron has a negative electric charge of -1.6 × 10^-19 coulombs, and a mass of about 9.10 × 10^-31 kg (0.51 MeV/c2), which is 1/1800 of the proton mass. When electrons move, free of the nuclei of atoms, and there is a net flow, this flow is called electricity, or an electric current

The nucleus (atomic nucleus) is the center of an atom. It is composed of one or more protons and usually some neutrons as well. The simplest atom of all, hydrogen, has one particle—called a proton—in its nucleus.

Proton is a subatomic particle with a positive fundamental electric charge of 1.6 × 10^-19 coulomb and a mass of 938 MeV (1.6726231 × 10^-27 kg, or about 1800 times the mass of an electron).

Neutron is a subatomic particle with no net electric charge and a mass of 940 MeV (very slightly more than a proton). Its spin is 1/2. The nucleus of most atoms (all except the most common isotope of Hydrogen, which consists of a single proton only) consists of protons and neutrons. Outside the nucleus, neutrons are unstable and have a half-life of about 15 minutes, decaying by emitting an electron and antineutrino to become a proton.

Electron (also called negatron, commonly represented as e−) is a subatomic particle which carries a negative charge. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. The electron has a negative electric charge of -1.6 × 10^-19 coulombs, and a mass of about 9.10 × 10^-31 kg (0.51 MeV/c2), which is 1/1800 of the proton mass. When electrons move, free of the nuclei of atoms, and there is a net flow, this flow is called electricity, or an electric current.

Atomic Number:
The number of protons in an atoms nucleus is called the atomic number (Z), and determines which element the atom is (for example hydrogen, carbon, oxygen, etc.). In an atom of neutral charge, the number of electrons typically equals the atomic number.

Atomic Weight (A):
The atomic weight is the sum of neutrons and protons in the nucleus of the atom also called Mass Number.

Molecular Weight:
The molecular weight of a molecule is the sum of the atomic weights of the atoms making up that molecule. Thus the molecular weight of water (H₂O) is 2 × 1.00794 (for two hydrogen atoms) + 15.9994 (one oxygen atom), or 18.01528.

Isotopes:
Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. i.e. number of neutrons differs in the atomic nuclei. Isotopes are generally written as 12C or carbon-12, with the number denoting the total number of protons and neutrons in the atom. Four out of every five elements occur in nature as mixtures of isotopes.
Isobars have the same isotopic mass but different atomic number. e.g. Argon, Potassium and calcium 18Ar40, 19K40 , 20Ca40
Isotone contains the same number of neutrons but different numbers of protons.

Sodium
Sodium is a constituent of many household products, including table salt and baking soda. In its pure form, however, it reacts explosively with water and oxidizes immediately upon exposure to the atmosphere. Reactions that produce useful chemicals can also cause environmental problems. Sulfur dioxide (SO₂), for instance, produced by burning sulfur in air is the precursor of sulfuric acid (H2SO₄), which in turn is used to produce fertilizer. Sulfur, however, is a common impurity in fossil fuels used for home heating and the production of electricity. Large amounts of SO² are thus produced under uncontrolled conditions, causing both local air pollution as well as the larger problems of acid rain.

The halogens
The halogens are a chemical series. They are the elements in Group 17 (old-style: VII or VIIA) of the periodic table: fluorine, chlorine, bromine, iodine, and astatine.

·         Chlorine gas is greenish yellow, is two and one half times as heavy as air, has an intensely disagreeable suffocating odor, and is exceedingly poisonous. It is a powerful oxidizing, bleaching, and disinfecting agent. Chlorine is an important chemical in water purification, in disinfectants in bleach and in mustard gas.

·         Bromine is a red volatile liquid at room temperature which has a reactivity between chlorine and iodine.

·         Astatine is radioactive and heaviest of Halogens.

·         Iodine is a bluish-black, lustrous solid and least reactive halogen. The deficiency of Iodine causes Goitre. Potassium Iodide is used in Photography. Iodine 131 is used as a tracer in medicine.