The history of the atom

Question 1

What did John Dalton propose about the atom?

Answer 1

• Cannot be split nor divided

- Are tiny, hard spheres

Question 2

What did J.J Thomson propose?

Answer 2

• Plum Pudding model
• Atoms are positively charged spheres
• With negatively charged particles (electrons)

Question 3

What did Rutherford and Marsden propose?

Answer 3

• The Nuclear model
• Positive alpha particle shot at gold foil
• Particle went through, went through + diverted, repelled
• Suggested empty space, negative charge is present (electrons), positive charge in nucleus (protons)
• There was a negative cloud in the atom

Question 4

What did Rutherford and Marsden propose?

Answer 4

• The Nuclear model
• Positive alpha particle shot at gold foil
• Particle went through, went through + diverted, repelled
• Suggested empty space, negative charge is present (electrons), positive charge in nucleus (protons)
• There was a negative cloud in the atom

Question 5

What is Bohr propose about the Nuclear model?

Answer 5

• Negative cloud would draw to positive nucleus (proton), atom would collapse
• Atoms has shells where electrons reside

Question 6

What is James Chadwick propose?

Answer 6

• To explain missing mass in atoms: neutrons

- No charge, same mass as proton (1)