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thomson's atomic model, plum pudding model, geiger-marsden experiment, alpha particle scattering, Thomson's model vs Rutherford's model, Thomson, Rutherford, Difficulties with Rutherford's model, atomic spectra, line spectrum, Atomic spectra: line spectra and series, bohr's postulates.

Is this for Class 12 Maharashtra HSC Physics?

Yes, it is written for the Maharashtra HSC Physics syllabus.

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Structure of Atoms and Nuclei — Class 12 Maharashtra HSC Physics revision notes

A 7-page visual revision sheet for Structure of Atoms and Nuclei, written for Class 12 Maharashtra HSC Physics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

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Structure of Atoms and Nuclei in one look

Rutherford found the nucleus, Bohr made it stable, and the nucleus itself hides the energy of stars and reactors

Thomson's atomic model

Thomson discovered the electron (1897) from cathode rays, disproving Dalton's indestructible atom
plum-pudding model (1898): a uniform positive sphere with embedded electrons, net charge zero
explains why only negative electrons are ever emitted, and why atoms form ions
could not explain the Geiger-Marsden scattering result that followed

Geiger-Marsden experiment

alpha particles (helium nuclei) aimed at thin gold foil, flashes counted at each angle θ
most alpha particles passed straight through: the atom is mostly empty space
about 1 in 8000 deflected past 90 degrees, a very few bounced back near 180 degrees
large-angle scattering needs a small, massive, positive core, not Thomson's spread-out charge

Thomson's model vs Rutherford's model

Thomson

positive charge spread through the whole atom
electrons embedded in it, like fruit in a pudding
predicts only small deflections, never a large one

Rutherford

charge and 99.9% of mass in a tiny nucleus, ~10 fm
electrons revolve around it, mostly empty space between
explains large-angle scattering as a close nuclear approach

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What this Structure of Atoms and Nuclei sheet covers

thomson's atomic model
plum pudding model
geiger-marsden experiment
alpha particle scattering
Thomson's model vs Rutherford's model
Thomson
Rutherford
Difficulties with Rutherford's model
atomic spectra
line spectrum
Atomic spectra: line spectra and series
bohr's postulates
bohr's atomic model
Radius and speed of the nth orbit
radius, hydrogen-like atom of atomic number Z
Bohr radius, n=1, Z=1
orbital speed
energy of electron
ionization energy
excitation energy
Energy of the nth orbit
total energy, hydrogen-like atom
ground state of hydrogen, n=1
photon emitted on a transition, m to n, m>n
Energy and radius: the limits
Rydberg formula
wave number of an emitted line
Rydberg constant
de broglie explanation
limitations of bohr's model
De Broglie's explanation and limitations of Bohr's model
Protons
Neutrons
Nucleons
atomic mass unit
unified atomic mass unit
Units for nuclear masses
Size and density of the nucleus
nuclear radius
nuclear density, since volume goes as A
typical value
nuclear force
strong force
The nuclear force
mass defect
binding energy
Mass defect and binding energy
binding energy per nucleon, a measure of stability
Binding energy per nucleon vs mass number
peaks near
typical mid-range value
hydrogen, single proton
radioactive decay
alpha decay
beta decay
gamma decay
Radioactive decay: alpha, beta, gamma
What each decay changes
decay law
half-life
average life
activity
The decay law
activity, rate of decay
number remaining
average (mean) life
The decay curve: special points
nuclear fission
nuclear fusion
Nuclear fission vs nuclear fusion
Fission
Fusion
chain reaction
nuclear reactor
Chain reaction and the nuclear reactor
X-rays: the tube, the spectrum, Moseley
Collisions of electrons with atoms
Traps that cost marks
Tricks that save time

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