NEET Physics | Modern Physics — Atoms & Nuclei
NEET PHYSICS
Modern Physics: Atoms & Nuclei
Complete Chapter Notes | Formulas | Quick Revision | Practice Questions
Compiled for NEET aspirants — concise, exam-focused, and formula-first.
Page 1
, NEET Physics | Modern Physics — Atoms & Nuclei
1. Atomic Models
1.1 Rutherford's Model
•Proposed after the alpha-particle scattering
experiment (gold foil experiment).
•Atom has a tiny, dense, positively charged nucleus at
the center; electrons revolve around it in circular
orbits.
•Most of the atom's mass is concentrated in the
nucleus; most of the atom's volume is empty space.
•Limitation: could not explain why electrons don't
spiral into the nucleus (classical EM theory predicts
radiating, energy-losing electrons).
NEET Tip: Rutherford's model failed to explain atomic
stability and the line spectrum of hydrogen — this is
exactly why Bohr's model is asked immediately after in
most NEET papers.
1.2 Bohr's Model — Postulates
•Electrons revolve in certain stable, non-radiating
orbits called stationary orbits.
•Angular momentum of the electron is quantized: L =
nh/2π, where n = 1, 2, 3...
•Energy is emitted or absorbed only when an
electron jumps between orbits, as a photon of
energy hν equal to the energy difference.
Page 2
NEET PHYSICS
Modern Physics: Atoms & Nuclei
Complete Chapter Notes | Formulas | Quick Revision | Practice Questions
Compiled for NEET aspirants — concise, exam-focused, and formula-first.
Page 1
, NEET Physics | Modern Physics — Atoms & Nuclei
1. Atomic Models
1.1 Rutherford's Model
•Proposed after the alpha-particle scattering
experiment (gold foil experiment).
•Atom has a tiny, dense, positively charged nucleus at
the center; electrons revolve around it in circular
orbits.
•Most of the atom's mass is concentrated in the
nucleus; most of the atom's volume is empty space.
•Limitation: could not explain why electrons don't
spiral into the nucleus (classical EM theory predicts
radiating, energy-losing electrons).
NEET Tip: Rutherford's model failed to explain atomic
stability and the line spectrum of hydrogen — this is
exactly why Bohr's model is asked immediately after in
most NEET papers.
1.2 Bohr's Model — Postulates
•Electrons revolve in certain stable, non-radiating
orbits called stationary orbits.
•Angular momentum of the electron is quantized: L =
nh/2π, where n = 1, 2, 3...
•Energy is emitted or absorbed only when an
electron jumps between orbits, as a photon of
energy hν equal to the energy difference.
Page 2
