The document summarizes the early models of the atom, including the plum pudding model, Rutherford's gold foil experiment, Bohr's model, and quantum numbers. The plum pudding model proposed that atoms are made of positive and negative charges distributed uniformly, like a plum pudding, but it did not explain the stability and positions of electrons. Rutherford's gold foil experiment showed that atoms have a tiny, positively charged nucleus at the center with electrons in the space around it. Bohr's model proposed that electrons orbit the nucleus in specific allowed orbits or energy levels without radiating energy. Quantum numbers were later introduced to further describe the specific states of electrons in atoms.

1. Structure of Atom

4. Atom

8. Electron = proton
He studies atom like plum pudding. Also called plum pudding model.
Limitation-
Doesn't explain stability and positon of electron in atom.

9. Ruther ford and his student conduct
experiment called Rutherford scattering
experiment/ gold foil Experiment/ alpha
particle scattering experiment.

15. 90% pass the gold
file remaining reflect
different direction.

16. Atom have tiny
positive
nucleus at
center.
Atom have tiny
electron
revolve around
the nucleus.

17. Limitation rutherford
• Position of electrons: The exact positions of the
electrons from the nucleus are not mentioned.
• Stability of the atom: According to the law of
electro–dynamics, the electron should therefore,
continuously emit radiation and lose energy. As a
result of this a moving electron will come closer
and closer to the nucleus

18. Postulates of Niels Bohr Atomic Theory
• Electron moves in circular orbit
around the nucleus. By attractive
force is centripetal F.
• electron can revolve only in those
orbits whose angular momentum
(mvr) is an integral multiple of
factor h/2π .
• As long as an electron is revolving in
an orbit it neither loses nor gains
energy. Hence these orbits are
called stationary states.
Niels Bohr 1885
• e- absorb or emit certain amount of energy.

20. Dual nature of electron

25. Quantum number
“The no. which identify state of electron,
specific energy associated with it and its
location around the nucleus.”
There are a total of four quantum numbers:
1. Principal quantum number (n),
2. Angular momentum quantum number (l),
3. Magnetic quantum number (ml),
4. Electron spin quantum number (ms).

34. Afbau Principle
This principle states that the electrons are
added one by one to the various orbitals
in order of their increasing energy starting
with the orbital of lowest energy. The
increasing order of energy of various
orbital is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s,
4d, 5p, 6s, 4f, 5d, 6p, 5f, 6d,
7p……………………