intro to atomic structure....

2. BASIC CONSTITUENTS OF MATTER
KANADA ,the Hindu sage who lived in
India during 6th century ,put forward
the theory that everything in the
universe was made of minute
particles calledPARAMANU

3. In 4th century BC, the
Greek philosophers
LEUCIPPUS and
DEMOCRITUS suggested
that the universe was
formed of very tiny
particles named ATOMS

4. Greek philosophers Plato
and Aristotle did not
approve atomic theories.
They argued that the
universe is formed of
four elements viz. soil,
water, air and fire.

5. LUCRETIUS, a Roman who
lived in 1st century BC,
put forward the idea that
substance were made of
indivisible particles.

6. According to thepanchabhutha theory that prevailed in
ancient India, the universe was made of the
panchabhuthas namely Vayu, Jalam, Bhoomi,
Akasham and Agni

7. LAW OF CONSERVATION OF MASS
Mass is neither created nor destroyed in a
chemical reaction

8. LAW OF DEFINITE PROPORTION
There exist a simple whole
number ratio between
the masses of the
combining elements in a
compound.
eg; pure water obtained from
different sources always
contains hydrogen and
oxygen combined in the ratio
1:8 by mass.

9. DALTONS ATOMIC THEORY
Matter is made up of very small particles called
atoms.
Atoms cannot be divided during chemical
reaction.
Atom can neither be created nor be destroyed.
Atoms of the same elements will be identical in
properties, size and mass.
Atoms of different elements will have different
properties and masses.
Atom is the smallest particle that can take part
in chemical reaction.
Atoms of two or more elements combine in a
small ratio to form compounds.

10. RELATIVE ATOMIC MASS
The mass of any atom is expressed by comparing it with the mass of a particular
atom.
1/12th mass of a carbon atom with atomic mass 12 (carbon-12)is now accepted as
the atomic mass unit (u).