Developing ideas of the atom through time

Question 1

What were the two main ideas about matter in ancient Greece?

Answer 1

• matter was made out of tiny bits

- matter was continuous

Question 2

Expand on the ideas about matter being made up of tiny bits, including who supported this idea and what they were right/wrong about.

Answer 2

• Leucippus of Meletus supported this idea

It was believed, rightly, that:

• all matter was made of particles that were too small to see
• atoms had different sizes and masses

It was believed, wrongly, that:

• Atoms were the same all the way through
• atoms could not be divided into anything smaller

Question 3

Who was a supporter of continuous matter and what else did he believe?

Answer 3

Aristotle; he believed that
everything was made of different combinations of the four elements (earth, water, air, fire)
matter could be divided without end

Question 4

What effect did aristotle’s ideas have on the progression of science?

Answer 4

They held it back

Question 5

Name the years that these scientists made an important development in science…

a) John Mayow
b) John Dalton
c) Henri Becquerel
d) JJ Thompson
e) Robert Boyle
f) Earnest Rutherford

Answer 5

a) John Mayow - 1600’s
b) John Dalton - 1896
c) Henri Becquerel - 1896
d) JJ Thompson - 1897
e) Robert Boyle - 1661
f) Earnest Rutherford - 1911

Question 6

What did John Mayow discover and how did he discover this?

Answer 6

• he discovered that air cannot be a single element as it must contain at least two different gases
• he discovered this by burning a candle in a jar and seeing the amount of air decrease

Question 7

When Robert Boyle published the Sceptical Chemist, what did he rightly suggest (2)

Answer 7

1. that some substances cannot be made simpler i.e. the chemical elements
2. that tiny particles made up all matter by joining together in different ways

Question 8

What was Robert Boyle wrong about?

Answer 8

He said the atom was indivisible

Question 9

Name two things John Dalton was right about and two things he got wrong.

Answer 9

Correct:
1. All atoms for a particular element have the same mass
2. Atoms do not change in a chemical reaction they get rearranged to form the products
Incorrect-
1. elements are composed of indivisible atoms
2. atoms cannot be broken down

Question 10

What did Henry Becquerel discover and what did this prove?

Answer 10

Radioactivity; proving particles could come from the atom and hence they are not indivisible

Question 11

What did JJ Thompson discover?

Answer 11

the first sub atomic particle - The electron

Question 12

Name three of JJ Thompsons correct findings about electrons

Answer 12

1. Electrons were negatively charged
2. electrons from all different elements were the same
3. electrons were located in the atom in circular arrays

Question 13

Although he discovered the electron, his findings also increased knowledge about other subatomic particles. explain how

Answer 13

• he realised there must be something with a positive charge in the atom
• he realised there must be something that accounted for the rest of the mass since atoms weighed a lot more than electrons

Question 14

Explain the plum pudding model

Answer 14

The plum pudding model had a positively charged sphere with electrons in circular arrays like plums in a plum pudding

Question 15

What is a scientific model?

Answer 15

Something scientists use to demonstrate their ideas

Question 16

What did Earnest Rutherford find?

Answer 16

That most of the mass and all of the positive charge of an atom was in a tiny central nucleus