2.1.1 The Changing Atom Flashcards
1
Q
Which Greek philosopher developed the first idea of the atom?
A
Democritus
2
Q
What did Dalton’s atomic theory propose?
A
- Atoms are tiny particles that make up elements.
- Atoms cannot be divided.
- All atoms of a given element are the same.
- Atoms of one element are different from those of every other element.
3
Q
Who proposed the plum-pudding model?
A
J.J Thomson
4
Q
What did the plum-pudding model propose?
A
Atoms are made up of negative electrons moving around in a ‘sea’ of positive charge.
5
Q
What did Rutherford’s model of the atom propose?
A
- The positive charge of an atom and most of its mass are concentrated in a nucleus, at the centre.
- Negative electrons orbit this nucleus, just as planets orbit the sun.
- Most of an atom’s volume would be the space between the tiny nucleus and the orbiting electrons.
- The overall positive and negative charges must balance.
6
Q
What did Bohr’s planetary model suggest?
A
Electrons orbit a central nuclear ‘sun’ in ‘shells’.
7
Q
Who discovered the proton?
A
Rutherford
8
Q
Who proposed wave-particle duality?
A
Louis de Broglie
9
Q
Who discovered the neutron?
A
James Chadwick
