Chapter 4.1 Notes

advertisement
Chapter 4.1 – The Development of Atomic
Theory
1. Democritus –
- Greek philosopher, 4th century BCE
- suggested universe was made of indivisible units called
atomos – means unable to be cut or divided
- did not have any evidence
- forgotten until 1700’s
Chapter 4.1 – The Development of Atomic
Theory
2. John Dalton –
- English school teacher, 1808
- atoms could not be divided
- all atoms of a given element were exactly alike
- atoms of different elements could join to form compounds
- developed the law of definite proportions – a chemical
compound always contains the same elements in exactly the
same proportions by mass
Chapter 4.1 – The Development of Atomic
Theory
3. J.J. Thomson –
- British scientist, 1897
- studied cathode rays
- experiments suggested cathode rays were negatively charged
particles from inside an atom
- discovered electrons – subatomic particles with a negative
charge
- proposed the plum-pudding model – electrons are spread
throughout the atom
Chapter 4.1 – The Development of Atomic
Theory
4. Ernest Rutherford –
- British scientist, 1911
- proposed most of the mass of the atom was concentrated at the
atoms center
- conducted gold-foil experiment
- discovered the nucleus – the atom’s central region made up of
protons and neutrons
- Rutherford’s model – negative electrons orbit the positive
nucleus
Download
Related flashcards

Boron compounds

30 cards

Sulfur compounds

48 cards

Phosphorus compounds

14 cards

Manganese compounds

33 cards

Titanium compounds

30 cards

Create Flashcards