1. History and Structure of the Nuclear Atom

2. The Atom
smallest particle of an element that retains all properties of the element.

3. I. Early Models of the Atom
Democritus (460 B.C. – 370 B.C)
first to suggest the existence of atoms
believed atoms were indivisible and indestructible

4. Name of theory Billard Ball Model B. Dalton
Atoms of the same element are identical
Each element is unique
Atoms combine in fixed ratios to form compounds
Name of theory
Billard Ball Model

5. C. J.J. Thomson Name of theory Plum Pudding Model Discovered electron
Suggested atom looked like plum pudding (or a blueberry muffin or chocolate chip cookie) with electrons evenly distributed throughout positive sphere
Name of theory
Plum Pudding Model

6. D. Rutherford
Conducted gold foil experiment

7. What did Rutherford expect?
Gold Foil Experiment Animation and Discussion

8. What did Rutherford actually see?

9. D. Rutherford Name of theory Nuclear atom
Conducted gold foil experiment
Proposed atom is mostly empty space
Concluded all positive charge and mass is concentrated in small region called nucleus
Name of theory
Nuclear atom

10. D. Rutherford
All the positive charge and all the mass of the atoms was concentrated in a small region called the nucleus
“This is almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.” – Rutherford, 1938

11. E. Bohr depicts the atom as a small, positively charged nucleus
surrounded by electrons that travel in circular orbits around the nucleus
Name of theory
Planetary Model

12. Quantum Mechanical Model or Electron Cloud Model
F. Schrödinger
model allowed the electron to occupy three-dimensional space like an electron “cloud”
Used a mathematical equation to show a model of electrons as waves
Name of theory
Quantum Mechanical Model or Electron Cloud Model

13. II. More about the Atom A. Size Teeny tiny
observable with instruments such as a scanning tunneling microscope.

14. B. Parts (called Subatomic Particles)
Protons: p+
charge = positive +1
mass =1
Electrons: e-
charge = negative -1
mass ~0
Neutrons: no
- charge = zero
- mass = 1

15. C. Location of Parts Nucleus: center of atom Outside nucleus:
contains protons and neutrons
has a positive charge
contains almost ALL of the mass of the atom
Outside nucleus:
Contains electrons
Has a negative charge
Occupies almost ALL of the volume of the atom

16. D. Atomic Charge Atoms are NEUTRAL # of protons = # of electrons
(ALWAYS if you’re talking about an ATOM)

17. Fun Facts
The volume of a hydrogen nucleus is a trillion times smaller than the volume of a hydrogen atom, yet the nucleus contains most of the mass.
If the nucleus (proton) of a hydrogen atom were as large as the width of a human thumb, the electron would be on the average about one kilometer away in a great expanse of empty space.