Lesson 1: History of the atom Flashcards
Who chronologically came first in developing the model of the atom?
John Dalton
When was Dalton’s theory developed?
1800’s
Who did Dalton base his ideas first?
Greek Philosophers, Democritus and Leucippus, who though that there was a limit to the size that things could be broken down into - atoms
What did Dalton discover?
That when he reacted two elements together, they always reacted in the same proportions. Based on this he stated that elements are made of one type of atom and compounds are formed of different elements combined together
Who used Dalton’s theory about atoms to create the periodic table and how?
Drimtrii Mendeleev - each element is made up from only one type of atom and different types of atom can be ranked by their proportional mass
What did Joseph Thomson discover?
The electron
What year did Thomson discover the electron?
1897
How did Thomson discover the electron?
He weighed the particles from a cathode ray tube and found they were 1800 times lighter than the hydrogen atom
What did Thomson disprove?
Dalton’s theory that the atom could not be split
What was Thomson’s model called?
Plum Pudding model
What did the Plum Pudding model look like?
It was like a positively charged circle/ball with electrons moving around inside the ball.
What else did Thomson discover about the electron?
He realised that the electrons are the same tiny particles that are emitted by radioactive and photoelectrical materials.
What did Ernest Rutherfors believe?
He agreed with Thomson;s idea that there are elctrons but he thought that the mass is concentrated in the nucleus - he called it the nucleus
When did Rutherford propose his model of the atom and what was it called?
He proposed the nuclear model in 1911, after being the first person to split the atom
Where did each electron orbit the nucleus in the nuclear model?
Each in their own paths
