Boron(B)
Compounds relevant to study of Boron
Borax (Na two B four O seven) Calamnite (Ca two B six O eleven)
Boron Trioxide (B two O three) Boric Acid (H three B O three)
Boron Nitride (B N)
Sodium Carbonate (Na two C O three)
Boron belongs to 13th group. It has a high melting point.
It is extracted from minerals Borax or Calamnite
Silicon (Si)
Compounds relevant to study of Boron
Silica (Si O two)
Silicon Halide (Si X four) X is for halogen
Sulphur (S)
Compound relevant to study of Sulphur
Hydrogen Sulphide (H two S)
Sulphur Dioxide (S O two)
Sodium Thio-Sulphate (Na two S two O three)
Ions formed by Sulphur
Sulphide ion (S O three (two-))
thiosulphate ion (S two O three (two-))
Sulphur occurs in the native as well as combined form.Large quantites of sulphur are obtained from underground deposits in USA.
Partial combustion of Hydrogen sulphide produce sulphur.
Reaction of Hydrogen Sulphide with Sulphur dioxide also gives sulphur.
Sulphur occurs as S eight. It is a puckered ring with crown conformation.
several allotropic forms of sulphur are available.
Rhombic sulphur (or alpha sulphur) is the stablest form. It is obtained by evaporation of solution of sulphur in carbon disulphide.
At about 95 C - 96 C rhombic sulphur is changed into another allotropic form monoclinic sulphur (als known as prismatic or beta sulphur).
Monoclinic sulphure has needle shaped crystals.
Other allotropic forms are amorphous (or colloidal) and plastic sulphur (or Gamma sulphur).
Amorphous sulphur is obtained by (1) the action of dilute Hydrochloric acid on sodium thio sulphate solution, and
(2)by passing Hydrogen sulphide through dilute nitric acid.
Plastic sulphur is obtained by pouring boiling sulphur in cold water. This results in rapid cooling. Plastic sulphur consists of a completely random arrangement of chains of sulphur atoms. On standing it passes over to the crystalline rhombic sulphur.
Sulphur is also active element like Oxygen. It combines with a large number of metals and nonmetals.
Sulphur is oxidized by concentrated nitric acid and sulphuric acid.
It also reacts with hot concentrated solution of alkalies.
See for some more details and diagrams on sulphur
http://www.alevelchemistry.co.uk/Module_4/HTML%20Files/oxy_acids_of_non_metals/7.8.1_Sulphur_Chemistry_Notes.htm
Halogens
Flourine (F), Chlorine (Cl), Bromine (Br), Iodine (I).
Chlorine is yellow green gas
Bromine is reddish brown liquid
Iodine is steel grey solid
Carbon
Carbon has two allotropic forms - diamond and graphite. Other amorphous carbons are actually micro crystals of graphite.
Diamond, an allotrope of Carbon is face centered crystal. It is the hardest natural substance. It is a nonconductor of electricity. It has high refractive inded (2.45) and much of the light that falls on it is internally reflected.
Diamond burns in air at 900 C and in oxygen at 700 C and forms carbon dioxide.
Graphite has a layer like structure in the three dimensional space and this gives it the lubricating property.
The carbon content of various amorphous forms of graphite; Peat (60%), Lignite (70%), Bituminous coal (78%) Semibituminous coal (83%) and Anthracite Coal (90%). The residue that remains after destructive distilation of coal in the absence of air is coke.
Ozone
Ozone (O three) is an allotropic form of Oxygen.
It is naturally formed above 20 Km from the earth from oxygen by absorbing sunlight. Ozone layer protects earth from concentration of ultraviolet rays. chlorofluorcarbons (C Cl two F two) used as refrigerant releases active chlorine after absorbing sunlight and this active chlorine decomposes ozone leading to destruction of ozone layer.
It is thermodynamically more stable than diamond.
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