Topic 4a- History of the atom Flashcards
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
