An element is defined by the IUPAC as a pure chemical substance composed of atoms with the same number of protons in the atomic nucleus. All atoms of an element have the same number of protons. Atoms of elements can have different number of electrons and neutrons.
A variant of an element with different number of neutrons is known as its Isotope
Different physical form of an element is known as its (e.g. graphite and diamond) Allotrope
Element most abundant in the Universe - Hydrogen
Element most abundant in the human body - Oxygen
Element which forms more than 10 million compounds - Carbon
Element with the lowest melting and boiling point - Helium
Element with the highest melting point - Carbon
Element with the highest boiling point - Tungsten
Element with highest density - Osmium
Element with lowest density - Hydrogen
Element with highest electronegativity Flourine
Element with lowest electronegativity (highest electropositivity) - Francium
The first element to be produced artificially - Technitium
The most corrosion resistant element (which cannot be affected by water, chemicals or acids) - Iridium
The element which was discovered on the Sun before it was found on the Earth - Helium
The non-metallic element which is liquid at room temperature - Bromine
The metallic element which is liquid at room temperature - Mercury
The most reactive element - Flourine
The Periodic Table was created by Dmitry Mendeleyev, a Russian chemist and professor in 1869.
The Periodic Table has seven rows or periods.
The present Periodic Table has room only for 118 elements.
Lanthanides is a group of 15 elements from atomic number 57 to 71. Together with Scandium and Yttrium they are known as rare earth elements.
Rare earth elements which are 17 in number are actally not rare. Most of them are commonly found
Actinides is a group of 15 elements from atomic number 89 to 103. All actinides are radioactive.
The Periodic Table has 18 columns or groups. Some important groups are listed below.
Group 1 - Alkali metals or Lithium group consists of Lithium, Sodium, Potassium, Rubidium, Cesium and Francium. Hydrogen is not an alkali metal even though it is listed in the first column.
Group 2 - Alkaline earth metals or Beryllium group consists of Beryllium, Magnesium, Calcium, Strontium, Barium and Radium.
Group 15 - Pnictogens or Nitrogen group consists of Nitrogen, Phosphorus, Arsenic, Antimony, Bismuth and Moscovium.
Group 16 - Chalcogens or Oxygen group consists of Oxygen, Sulphur, Selenium, Tellurium, Polonium and Livermorium.
Group 17 - Halogens or Flourine group consists of Flourine, Chlorine, Bromine, Iodine, Astatine and Tennessine.
Group 18 - Noble gases or Helium or Neon group consists of Helium, Neon, Argon, Krypton, Xenon, Radon and Oganesson.
Sodium tetraborate decahydrate
Aqueous sodium chloride solution
Plaster of paris
natural Calcium sulfate
Aluminium potassium sulfate
HNO3 + 3 HCl
Corundum (ruby, sapphire)
2H2O or D2O
Important and Useful Chemicals
Chemical with which flourescent lamps are coated for providing illumination - Phosphor
Chemical used to remove rust stains from clothes - Oxalic acid
Chemical with which photographic films are coated - Silver Bromide
Chemical in which gold dissolves - Aqua Regia
Chemical with which non-stick cookware is coated - Teflon
Chemical used in the manufacture of matches - Phosphorus
Chemical used to purify water (as a disinfectant) - Chlorine
Chemical used as an antiseptic in mouth freshner, toothpastes etc. - Hydrogen Peroxide
Chemicals used in the breath test to check drunken driving - Potassium dichromate and Sulphuric acid
Chemical used as a purgative - Magnesium Sulphide
Chemical used in cloud seeding - Silver Iodide
Chemical used as a fixing agent in photography and also for washing as a germicide - Sodium thiosulphate
Chemical commonly used in explosive devices as well as fertilisers - Ammonium Nitrate
The substance which is used to make capsule shells in pharmaceutical industry. The substance is also used as gelling agent in cooking. - Gelatin
The sugarcane industry product being blended with petrol to reduce pollution and also to reduce the import burden of petrol in India - Ethanol
The organic compound widely used as a cleaning agent in dry cleaning - Tetrachloroethylene (perchloroethylene)
The chemical commonly used in baby diapers for its super absorbent properties - Sodium polyacrylate
The chemical used for embalming bodies and preservation of animal specimens and tissue samples - Formalin (aqeous solution of formaldehyde)
The compound which is used in moisturing creams and soaps because of its hygroscopic properties - Glycerol
The chemicals used to produce fog/smoke on theatrical stages or studios - 1. Dry ice 2. Glycol and water mix
The chemical used as anticoagulant in blood collection tubes and for the preservation of blood in blood banks - Sodium Citrate
The chemical commonly used as rodenticide - Zinc Phosphide
The chemical commonly used in sunscreen lotions, cigarette filters, ceramic industry - Zinc Oxide
Pink to Red
Corundum (Aluminium oxide Al2O3)
Quartz (Silicon dioxide SiO2)
Variety of colours
Hydrated silica (SiO2·nH2O)
Blue to greenish
Hydrated copper and aluminium phosphate [CuAl6(PO4)4(OH)8·4H2O]
Variety of colours
Aluminum silicate containing fluorine (Al2(F,OH)2SiO4)
Metamorphic rock with mineral lazurite as its chief constituent
Pale greenish blue or bluish green
Pink to orange-pink
Other Precious Materials
White (other colours are also possible but rare)
Argonite (Calcium Carbonate CaCO3))
Important Organic Acids
Chiefly found in
Citrus fruits like lemon, lime, orange
Sour apples, sour grapes
Grapes, tamarinds, pineapples
Rapeseed oil, Mustard oil
Properties of Acids
Acids have pH less than 7.
Acids turn blue litmus to red.
Acids have sour taste.
With bases - Acids react with bases to produce a salt and water.
With carbonates - Acids react with carbonates to produce salt, water and carbon dioxide.
With metals - Acids react with metals to produce a salt and hydrogen.
Pickling of steel
Gastric acid secreted by stomach mainly contains HCl.
Production of fertilisers
Nitric acid is produced by electric discharge in the atmosphere such as lightning. Known as Aqua Fortis in ancient times.
As an electrolyte in lead-acid batteries.
Known as Oil of Vitriol in ancient times.
Used in beverages like colas to give a tangy taste.
Etching (writing or marking) of glass
Stored in plastic containers.
Making of soft drinks and other bubbly drinks
CO2 in air combines with water in the ocean to form carbonic acid. Ocean acidification thus caused is of grave environmental concern.
It is a process in which electric current is passed through a substance to effect a chemical change. Usage : Electroplating, Production of pure form of some metals
It is a process of converting fat into soap by treating it with an alkali. Usage : Manufacture of soaps
It is a metabolic process in which sugar or carbohydrate is converted to acid, gas or alcohol. Usage : Making of wine, liqour, curd etc.
It is a process in which natural rubber is treated with sulphur to make it more durable and elastic. Usage : Manufacture of tyres
It is a process in which large fat globules are broken down into tiny droplets. The tiny droplets are uniformly distributed in an immiscible liquid to form emulsion.
Usage : Emulsions are used in paints, cosmetics, medicines etc.
It is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.
Usage : Used in frost-free refrigerators
It is a heat treatment process to kill bacteria in liquid food or beverages. Usage : Preservation of milk
It is a process of mixing carbondioxide in liquids under high pressure. Usage : Making of soft drinks
It is a process of separating the component substances from a liquid mixture by selective evaporation and condensation.
Usage : Separation of gasoline etc. from crude petroleum.