Atomic Models, Subatomic Particles, and Isotopes

J.J Thompson's Plum Pudding Model

Particles stuck to positive plate of cathode ray tube: therefore, particles are negative: discovering electrons

E. Rutherford's Gold Foil experiment & Nuclear Model

Fired alpha particles at Gold foil, but something in the middle of atom deflecting particles
Discovered Nucleus and Protons

N. Bohr and Planetary Model

Proposed that Electrons must orbit nucleus at fixed distances (shells) to not crash
Each shell has specific energy level associated with it: quantized ladder

J. Chadwick and Neutrons

Combined light elements and alpha particles to test where atoms' extra mass was coming from: resulted only heavier mass but not new identity, discovering neutrons

The Electron

Charge: -1 eV or -1.602 x 10-19 C
Symbol: e-
Mass: 5.486 x 10-4 amu - practically negligible mass and diameter
Discovered by J.J. Thompson in Cathode Ray Tube experiment
Further developed in Bohr's Planetary Model

Isotopes

Have the same atomic number as its main element, but a different number of neutrons, resulting in a different atomic mass.

Average Atomic Mass Equation

Average atomic mass = Σ (Isotope mass x Fractional Abundance)

The Uncertainty Principle

It is impossible to determine the position & momentum of electrons at the same time. Instead you can calculate the probability of an electron's location by getting the square of Schrodinger's Equation (KE+PE = Total Energy)

The Proton

Charge: +1 eV or +1.602 x 10-19 C
Symbol: P+
Mass: 1.0073 amu - significantly heavier than an electron
Discovered by E. Rutherford through Gold Foil experiment

The Neutron

Charge: 0 eV
Symbol: No
Mass: 1.008 amu
Discovered by J. Chadwick combining light elements and alpha particles