Saturday, July 7, 2012

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Pure substance


Pure substance
The substance that is made up of same kind of molecule in a mixed proportion by their number and weight. Eg:= nitrogen,oxygen.

Types of Pure substances

Element
The pure substance which cannot be broken into
two or more than two or more than two substance is called element.Eg:-Hydrogen, Oxygen, Neon, Helium etc. There are 111 elements in solid, liquid, gaseous state. 92 elements  are natural and remaining 14 are artificial.

Symbol of elements
A symbol is defined as an abbreviation of the full name of the element.They are represented by using English alphabets.They are made up either of one or two letter. If the symbol of the element has two letter,the first letter must be written in capital letter.
There are three ways of written in three ways

a)By using the first letter of the name of the element

S.N.
Elements
Symbol
1
Hydrogen
H
2
Oxygen
O
3
Carbon
C
4
Nitrogen
N
5
Fluorine
F
6
Sulphur
S
7
Boron
B
8
Phosphorus
P
9
Iodine
I
10
Uranium
U



b)If the name of two or more elements begins with the same letter ,the second letter with their names is also taken with the first letter

S.N.
Elements
Symbol
1
Helium
He
2
Lithium
Li
3
Beryllium
Be
4
Neon
Ne
5
Aluminium
Al
6
Silicon
Si
7
Argon
Ar
8
Calcium
Ca
9
Cobalt
Co
10
Nickel
Ni


c)Symbols are made by using the letters of the name of elements in other languages also

S.N
Elements
Name in Latin Language
Symbol
1
Sodium
Natrium
Na
2
Iron
Ferrum
Fe
3
Copper
Cuprum
Cu
4
Silver
Argentum
Ag
5
Gold
Aurum
Au
6
Tin
Stannum
Sn
7
Mercury
Hydrargyrum
Hg
8
Lead
Plumbum
Pb
9
Potassium
Kalium
K



Compound
A compound is a substance made up of two or more elements chemically combined in a fixed proportion. There are many compound. Eg:- water, carbondioxide etc.

Eg:- H2O
              H2+O=H2O
Two atom of hydrogen combine with an atom of oxygen.

Eg:- CO2
               C+O2=CO2
Two atom of oxygen combine with an atom of carbon.

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