Atoms and Molecules
We know that all the particles can be divided into smaller particles and we
shall divide smaller and smaller particles but a time comes where we can not
divide further to that particles.
Law of chemical Combination
After doing a lot of expirement the sciencetist conclude following two laws
Law of conservation of Mass
According to law of conservation of mass, mass neither be created nor be
destroyed in a chemical reaction.
Law of constant proportions
Many compounds were composed of two are more compound of same element in same
proportion.
Example :-
* In a compound of water, the ratio of hydrogen and oxygen is one ratio
eight. If we take 9 gram of water then it takes 1 gram of oxygen with 8 gram of
hydrogen.
* In a compound of ammonia, the ratio of nitrogen and hydrogen is 14 : 3.
If we take 17 gram of water then it takes 14 gram of nitrogen with 3 gram of
hydrogen.
In above examples we can understand that all the element in any compound
are in definite proportions by masses. According to law ‘In any chemical reaction
the compounds are in definite proportion by masses.’
It follows the law of conservation
of masses. Now a problem of explaining these equation takes place. To define
these problems scientist gave a name ‘Atom’. They explained that atom is the
smallest particle of matter. According to this theory all the compound, element
or mixture have smallest particle, that is Atom.
* All matter’s smallest particle is Atom.
* Atoms can not be created or destroyed in any chemical reaction.
* Identical in mass and chemical properties.
* Atoms combine in small whole numbers.
Atoms
Atoms are very small particle in our surrounding. It’s a smallest particles
in our universe which can image. It is two small in size so we are not able to
see these particles with our naked eyes. Millions of atom combined together and
forms a layer of thickness of paper.
Atoms of hydrogen have a radius of 10^(-10) and the radius of water
molecule is 10^(-9).
These atoms radius is too small so we are not able to see these with our
naked eyes.
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Its two small in size but its in all things. It effects all our activities.
In modern days we can see a layer of particles with magnifying it by different technique.
Scientist gives the symbols for element. All the element have a specific
symbol. It is the first or first two letter of element for example Oxygen have
symbol ‘O’ and nitrogen have a symbol of ‘N’.
In above discussion we conclude that all the symbol of elements represent a
definite quantity of that element. This is equal to the one atom of that
element. In earlier days name of element taken from its city of finding. For example
copper is taken from Cyprus. In a same time the of element is taken according
to there color, Gold is a example of that. These symbol are approved by IUPAC.
The first letter of the symbol is written in capital and second is written in
small letter.
For example :- In aluminum Al, In cobalt Co, In magnesium Mg etc
Other examples are chlorine Cl and zinc is Zn
Some other symbol are taken from Greek, German and Latin.
For example :- Symbol of Sodium is Na, Potassium is K and Iron is Fe etc.
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