CORE unknown things

Question 1

What were John Dalton’s theories of the atom, and what caused his original model to be changed?

Answer 1

• Atoms cannot be created, divided or destroyed.
• Atoms of the same element are exactly the same; atoms of different elements are different.
• Atoms join with other atoms to make new substances.
• The discovery of subatomic particles caused his model to change.

Question 2

How did JJ Thompson discover the electron?

Answer 2

• Thompson experimented with a cathode ray tube.
• The beam moved towards the positively charged plate so he knew the particles must be negatively charged.

Question 3

Describe the model proposed by JJ Thompson.

Answer 3

The plum pudding model consisted of negative electrons scattered through positively charged material.

Question 4

How did Ernest Rutherford disprove the plum pudding model?

Answer 4

• He shot a beam of positively charged alpha particles at a thin piece of gold foil.
• Most passed through, but some were repelled back; if the plum pudding model was true, all particles would pass through as the matter would be evenly distributed.
• This suggested a dense, positively charged nucleus.

Question 5

What is the relative mass of an electron?

Answer 5

1/1836

Question 6

What are the uses of graphite?

Answer 6

• Electrodes, because it conducts electricity and has a high melting point.
• Lubricants, because the layers of carbon slide over each other easily.

Question 7

What is a fullerene, and what are two examples?

Answer 7

• A molecule made of only carbon that is shaped as a ball or tube.
• Graphene
• Buckminsterfullerene (C60)

Question 8

What are the properties of buckminsterfullerene?

Answer 8

• Slippery (weak intermolecular forces)
• Low melting point
• Large surface area