1. 4.1 History of the
Atom

2. A. Democritus (Greek model)
First to say everything made of atoms
atomos – “uncuttable”
a means “not”
tomos means “cut”
Democritus quotes Leucippus: "The atomists hold that splitting stops when it reaches indivisible particles and does not go on infinitely."

3. Atomic Theory B. Dalton’s model A. All things are made of atoms. They
are indivisible and indestructible
B. Atoms of the same element are all
alike
C. Atoms of different elements are
different
D. Compounds are made from the
combination of two or more different
atoms

4. John Dalton

5. C. Thomson’s Model
studied electric current through a gas in a cathode ray tube
showed that the charge was negative
thought they came from inside the atom

6. video
J.J. Thomson
Cathode Ray tube

7. Problem

8. Thomson comes up with the
Plum Pudding Model

10. D. Rutherford’s Model

11. Video
Animation

12. E. Bohr Model
Planetary model electrons move about the nucleus of the atom like the planets move about the Sun.

14. Because Bohr was trying to explain Spectral lines of course !!!!!!!!!!
Why the planetary model ?
Because Bohr was trying to
explain Spectral lines of
course !!!!!!!!!!
Huh ?????
You Know spectral lines !!!!

16. Bohr’s atom explains only simple atoms like hydrogen
Problems
with the Bohr Atom
Bohr’s atom explains only
simple atoms like hydrogen
Bohr’s atom does not
explain more complex atoms

17. F. The Wave Model Electrons do not move about
the atom in a definite circular pattern.
It is impossible to determine
the exact location of the electron
Heisenburg Uncertainty Principle

18. Schrödinger's Atom (The wave model)
Electrons move in energy
levels, they are not just
round orbits

20. 4.2 Structure of the Atom

21. A. Subatomic Particles
Protons
Neutrons
Electrons

22. Atomic Symbol
Mass Number
charge
Element Symbol
Atomic Number

23. Proton + charge (each proton has a +1 charge)
Determines the atomic number
Found in the nucleus of the atom (Rutherford)

24. Electron - charge Determines the charge of the atom
Neutral same # protons as #electrons
Negative charge more electrons than protons
Positive charge fewer electrons than protons
Ion – atom where electrons do not equal protons
1 more electron than protons (-1 ion)
2 less electrons than protons (+2 ion)

25. Neutrons
neutral charge
Found in the nucleus of the atom

26. Atomic Number Number of Protons How the periodic table is arranged
Hydrogen has 1 proton (atomic number 1)
Oxygen has 8 protons (atomic number 8)
How the periodic table is arranged

27. Mass Number
Neutrons + Protons
99% of mass in nucleus

28. Isotopes Same kind of atom (same number of protons)
Different number of neutrons