1. Aim: What is the structure of the Atom?
Section 6-1

2. 1.) Structure of the Atom
a.) fundamental building blocks that make up all matter
b.) 3 subatomic particles which make them up
1.) protons, neutrons, and electrons

3. Subatomic particle
Charge
Mass
Location
Proton +1
1 amu
In nucleus
Neutron
Electron -1
1/1836 amu
In orbital

4. 2.) History A.) Democritus – suggested discontinuous theory of matter
B.) Dalton – Atomic Theory (solid sphere)
1.) elements are indivisible and indestructible (no subatomic particles)

5. C.) JJ Thomson – Plum Pudding model (1910s)
1.) Used a Crookes Tube which show a flow of electrons (cathode rays)
2.) cathode rays deflect toward positive electrode (rays are negative)
3.) atom is not the indivisible particle
4.) negative rays are made of subatomic particles called electrons

6. D.) Rutherford’s Gold Foil Experiment
1.) Shot alpha particles (Helium nuclei [positive particle]) at gold foil
2.) Most alpha particles passed directly through the gold foil
a.) atom is empty space
3.) Some deflected off
a.) have dense and positive nucleus

8. E. Bohr Model (Planetary Model)
1.) Electrons exist in energy levels
2.) Electrons stay in orbit, and don’t fall towards the nucleus
a.) electrons are in ground state which is the lowest possible energy of the atom
1.) the further a level is from the nucleus, the higher in energy the electron is.

9. F. The Charge-cloud model (wave-mechanical model)
1.) electrons are not in circular orbits, but are in orbitals.
a.) orbitals are areas that electrons are found