This document discusses four major atomic models: - Dalton's atomic theory from 1807 which proposed atoms of the same element are identical and atoms can combine to form new substances. - Thomson's "plum pudding" model from 1904 which viewed the atom as a positively charged sphere with electrons embedded within it. - Rutherford's 1909 "planetary model" based on his gold foil experiment, showing the atom consists of a small, dense nucleus surrounded by empty space with electrons orbiting the nucleus. - Bohr's 1913 model which introduced the concept of distinct electron orbits or shells around the nucleus to explain atomic spectra. This model is closest to how atoms are currently understood.

1. ATOM MODELS
VIJITHAMOL M.K
PHYSICAL SCIENCE

2. DIFFERENT ATOM MODELS
• Dalton's atom theory
• Thomson's atom model
• Rutherford's atom model
• Bohr model of atom

3. DALTON'S ATOMIC
THEORY (1807)

4. POSTULATES
Atoms of one element have masses that are
different from atoms of other elements
Atom of the same element are identical
An atom of one element can't be changed into
an atom of another element
Atoms of different element can be combined
and/or rearranged to form new substances

5. THOMSON'S MODEL OF ATOM
He invented electron in
the atom.His atom
model is known as
plum pudding model

6. PLUM PUDDING MODEL
◆Thomson thought that atoms consisted
of positively-charged main bodies,and
attached to these were the negatively-
charged electrons(plum pudding model)

8. RUTHERFORD MODEL OF ATOM
He done an experiment
known as gold foil
experiment to find the
inner structure of
atom.HIs atom model is
known as planetary
model.

9. GOLD FOIL EXPERIMENT

10. CONCLUSIONS OF THE EXPERIMENT
• Most of the space inside the atom is empty
• Positive charge of the atom occupies very
little space
• All positive charge and mass of the atom
were concentrated in a very small volume
within the atom

11. STRUCTURE OF ATOM
• Atom has a central part called nucleus.
• Nucleus is very small as compared to the size of
the atom.
• All positive charges and most of the mass of
atom are concentrated on nucleus.
• Negatively charged electrons are revolving
around the nucleus in a cercular path.

12. BOHR MODEL OF ATOM
He introduced this
model to solve the
drawbacks of Rutherford
model of atom.

13. CONCEPTS OF BOHR MODEL
• Electron revolve around the nucleus in fixed paths
called orbits or shells.
• Electrons in each she'll have a definite
energy.Hence shells are also called energy levels.
• As long as an electron revolves in a particular
orbits,its energy remains constant.
• The energy of the shells increases as distance from
the nucleus increase.
• The shells around the nucleus can be numbered
from near the nucleus as 1,2,3,4,..... or represented
by the letters K,L,M,N,........

14. STRUCTURE OF BOHR MODEL

15. CONCLUSION
This are the main models of
atom.Now we are using Bohr
model of atom.

16. THANK YOU