Chemistry - History of the Atom Flashcards
what was democritus’ atomic theory?
everything is made up of tiny particles seperated ny empty space
when was democritus’ alive?
500 BC
when did john dalton develop his theory?
1800s
how did Dalton describe atoms?
as ‘solid spheres’
how did JJ Thompson disprove Dalton’s theory?
he carried out numerous experiments contained a negative component, showing that they weren’t just ‘solid spheres’
What was the name of JJ Thompson’s model of the atom?
Plum Pudding Model
When did JJ Thompson create the plum pudding model?
1877
describe the plum pudding model
a ball of positive mass with negative electrons embedded
When did Rutherford do the alpha particle scatter experiment?
1909
what did the alpha particle scatter experiment involve?
shooting positive alpha particles at a thin sheet of gold
How did the alpha particle scatter experiment disprove Thompson’s plum pudding model?
Thompson’s model suggested that positive alpha particles would pass through the positive mass with little resistance. However, some alpha particles were deflected to the side and back in the direction they came
What did the alpha particle scatter experiment lead Rutherford to create
the nuclear model
describe Rutherford’s nuclear model
a compact nucles with all the positive charge surrounded by a negative force
Why was Rutherford’s nuclear model flawed?
there appeared to be nothing stopping the negative charge from rushing in and collapsing the atom
how did Niels Bohr fix the flaw of the Rutherford’s nuclear model?
he suggested that electrons orbited in shells, preventing it from collapsing
