Topic 4a- History of the atom Flashcards
(8 cards)
Who first theorised that matter was made of lumps called “atoms”?
Democritus
Who was the first person to agree with Democritus and when?
1804- John Dalton
Who formed the idea of the plum pudding model?
J J Thompson
What was the plum pudding model? Who came up with it, why and when?
~1900, JJ Thompson discovered atoms.
Plum pudding model → atoms were spheres of positively charged energy with random negatively charged electrons stuck in it like a “plum pudding”
What replaced the plum puding model? Who was behind it? When and why?
1909- Rutherford
Fired a beam of alpha particles at gold foil.
More alpha particles were reflected than expected which resulten in Rutherford concluding that:
- most atoms consisted of largely empty space
- nucleus of an atom has a large positive charge
- nucleus must be small and compact
Who are the 6 key scientists and their dates for the history of the atom
- Democritus [400BC]
- John Dalton [1804]
- JJ Thompson [~1900]
- Rutherford [1910]
- Niels Bohr [pretty soon after 1910]
- James Chadwick [1930]
Surnames: Don’t Dance The Rhumba Before Chachacha
what a squad.
What did Niels Bohr do?
Used evidence to prove electrons orbited the nucleus in energy shells
What did Chadwick do?
Discover the neutron
