Symbols and Formulae
Some typical symbols derived from Latin names:
English name Latin name Symbol
Sodium Natrium Na
Potassium Kalium K
Iron Ferrum Fe
Copper Cuprum Cu
Silver Argentum Ag
Gold Aurum Au
Tin Stannum Sn
Mercury Hydrargyrum Hg
Lead Plumbum Pb
Antimony Stibium Sb

→ German name of Tungsten is Wolfram & its symbol is W.
→ The term Atom was first used by Dalton in his atomic theory.
→ The term Molecule was first used by Avogadro in his ‘Avogadro’s hypothesis.
→ Dalton used the term compound atom instead of molecule.
→ Atom is the smallest particle that takes part in a chemical reaction.

Elements and Compounds
→ There are 92 natural elements and more than 31 artificial elements.
→ The compound is composed of elements in a fixed proportion.
→ A substance composed of two or more non-reacting compounds is a mixture.

Some Methods for the Separation of Mixture:

→ Filtration: used for separating an insoluble solid present in a liquid; e.g. BaSO₄ present in aqueous solution, CaCO₃ in water etc.
→ Distillation is used for purifying liquids that boil without decomposing.
→ Distillation is the best method for the separation of a 1:1 mixture of ortho and para nitrophenol; Ethyl alcohol & ether.
→ Absolute alcohol is prepared by azeotropic distillation.
→ Sublimation: Used for separating two solids eg. NH₄Cl, I₂, + sand, etc where one of the two solids is volatile.
→ Substance undergoing sublimation: NH₄Cl, I₂, dry ice (solid CO₂), naphthalene, benzoic acid, salicylic acid, corrosive sublimate (HgCl
), camphor, arsenic oxide, red phosphorus (in vacuum) etc.
→ Fractional distillation: applied if the boiling point of two liquids differ by 15–20°C eg: Benzene & toluene; methyl alcohol & acetone [BPKIHS 2003]
→ Distillation under reduced pressure or vacuum: Used for separating liquid that decomposes at boiling point. Eg. H
O glycerol [MOE 1997]
→ Steam distillation: Used for separating water-insoluble liquid from a mixture of two liquids by heating with water eg. Nitrobenzene, aniline, lemon oil, sandalwood oil etc.
→ Crystallization: Used to separate dissolved crystalline solid from its solution eg. CuSO₄ crystals from its aqueous solution.
→ Fractional crystallization: Used to separate two solutions that differ in solubility e.g.: KCl + KClO₃ (less soluble), Na
CrO7 + NaSO₄ (less soluble)
→ Solvent extraction: Used to separate two solids by means of a solvent. E.g. Sand + saltwater (used as solvent); I + water (chloroform used as solvent)
→ Mechanical separation: Separating two immiscible liquids with help of a separating funnel. Eg. Oil in water.
→ Magnetic method: For iron filling + sand; tinstone + wolframite. Here, one of the solids should be magnetic and the other should be non-magnetic.
→ Atmolysis: Used form mixture of gases or vapours based on the difference of rate of diffusion e.g. H
 + O₂

→ Latest technique to purify organic compounds [MOE 98]
→ Discovered by Tswet
→ Mobile/Moving phase – liquid or gas
→ Stationary/fixed phase – liquid or solid absorbed in solid
→ Suitable absorbents used in fixed phase: Alumina (Al
O), Silica gel (SiO), MgO/fuller’s earth.
→ Based on selective adsorption [IOM 1999, 1996]
→ In paper chromatography, the mobile phase is liquid and stationary in solid [IOM 1997]
→ Moisture is removed from substances by desiccation [IOM 2000]
→ A mixture of sand and powdered charcoal can be separated by washing [IOM 2000]

→ Isomorphs: molecules having the same number of atoms bonded in a similar fashion. E.g.
i. FeSO₄.7H
O, MgSO₄.7HO and ZnSO₄. 7HO
ii. KSO₄, KCrO₄ & KSeO₄
iii. Alums: Ammonium alum [(NH₄)SO₄.Al(SO)₃.24HO] and Potash alum [KSO, Al(SO4).24HO]

→ Isobars: atoms having the same mass number but different atomic numbers. E.g. 18Ar40, 19K40 & 20Ca40 are isobars.
→ Isobars have the same number of nucleons. [MOE 2055]
→ Isotopes: atoms having the same atomic no but different mass no. E.g. 1H1, 1H2, 1H3
→ 1 𝞪–decay followed by 2 β– decay produces an isotope of the parent atom.
→ Isotones: atoms having the same number of neutrons but different mass no E.g 14Si30, 15P31, 16S32@ Isotone = same no. of neutrons
→ Isomers: atoms having the same atomic number & mass number but different radioactive properties E.g. 35Br80
→ γ-decay produces isomer with parent atom
→ Isodiaphers: atoms having the same difference of neutron & proton (h–p)
→ 𝛼-decay produces isodiaphers of with parent atom.
→ Isoelectronic atoms or groups of atoms having the same no of electrons e.g. CO, CN⁻, NO
 are isoelectronic
→  Isoatomic: Having same no of atom e.g. NO & SO
→ Isosters: Isoelectronic + isoatomic e.g. NO & CO
 Isolobal: atoms having the same geometry & hybridization e.g. (SO₂, SnCl)
 An element has mass number 14 & number of neutron 8, then it is an Isotope of carbon. [MOE 2002]

Also, Read our other Notes of Physical Chemistry:

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