This document discusses the physics of atoms and their subatomic particles. It describes the Bohr model of the atom, which depicts electrons orbiting the nucleus in fixed orbits or shells. When electrons move between these shells, energy is absorbed or emitted in the form of radiation. The document also outlines the discoveries of subatomic particles like electrons, protons, and neutrons through experiments such as Rutherford's gold foil experiment and Chadwick's work. Finally, it provides the names, symbols, masses, and charges of the basic particles that make up an atom: protons, neutrons, and electrons.

1. PHYSICS OF ATOM
U S MA N S A N D H U
0 8 0 3 0 6 1 0 - 0 2 3

2. • Fundamental piece of matter.
• The protons and the neutrons make up the center of the atom called the nucleus and
the electrons fly around above the nucleus in a small cloud.

3. SUBCOMPONENTS AND QUANTUM THEORY

4. BOHAR MODEL OF ATOM
• The electron to move around the nucleus following fixed paths, or orbits, much as a
planet moves around the sun.
• This lowest energy state is called the ground state.

5. • It successfully predicted the
frequencies of the lines in the
hydrogen spectrum, so it seemed to be
valid.

6. MAIN POINTS OF THE BOHR MODEL
• Electrons orbit the nucleus in orbits that have a set size and energy.
• The energy of the orbit is related to its size. The lowest energy is found in the
smallest orbit.
• Radiation is absorbed or emitted when an electron moves from one orbit to another.

7. RUTHERFORD'S PLANETARY MODEL OF THE ATOM
• Rutherford tested Thomson's
hypothesis by devising his "gold foil"
experiment.
• Alpha particles

8. DISCOVERY OF THE ELECTRON
Electrons are bound to atoms they can – after
acquiring energy from their surroundings –
change their position tremendously fast.

9. DISCOVERY OF
NEUTRONS
• Chadwick’s work

10. DISCOVERY OF PROTONS
The Discovery of Radioactivity (Ernest
Rutherford)
• In 1899 Ernest Rutherford studied the
absorption of radioactivity by thin
sheets of metal foil and found two
components: alpha
Radiation affected by electric and
magnetic field

11. THE BASIC PARTICLES THAT MAKE UP AN ATOM
• Name symbol Approximate More accurate mass
Relative charge
• Relative mass
• Proton P 1 1.0000
+1
• Neutron n 1 1.0016
0
• Electron e Almost zero 0.000547
-1
•