C1

Question 1

What is a physical change?

Answer 1

When a substance changes state or shape or breaks into pieces
No new substances are made
Reversible

Question 2

What is a chemical change?

Answer 2

Produces one or more new substances
Properties of the new substance are different from the original
Difficult or impossible to reverse

Question 3

What happens to the particles in a physical (state) change?

Answer 3

Particles stay the same but arrangement and movement changes

Question 4

What happens to particles in a chemical change?

Answer 4

Particles break up and join together in different ways
This is why new substances are made

Question 5

What is the size of an atom?

Answer 5

3 x 10^-9m

Question 6

What is the radius of a nucleus

Answer 6

1 x 10^-14m

Question 7

What are electrostatic forces? (3)

Answer 7

Attractive forces between positive and negative charges in atoms
Forces are weaker the further apart from the particles
Strongest in solids, weakest in gases

Question 8

Limitations of the particle model: (3)

Answer 8

Doesn’t account for:
- forces between particles
- size of particles
- space between particles

Question 9

What is an atom?

Answer 9

The smallest particle of an element that still contains the chemical properties

Question 10

What is a molecule?

Answer 10

Made from two or more atoms joined together joined by attractive forces called chemical bonds

Question 11

What are the subatomic particles in an atom?

Answer 11

Protons
Neutrons
Electrons

Question 12

What is the relative mass of the subatomic particles?

Answer 12

Proton = 1
Neutron = 1
Electron = 0.0005

Question 13

What is the relative charge of the subatomic particles?

Answer 13

Proton = +1
Neutron = 0
Electron = -1

Question 14

What is the atomic number?

Answer 14

Number of protons (and electrons) in the nucleus

Question 15

What is the mass number?

Answer 15

Total number of protons and neutrons

Question 16

What is an isotope?

Answer 16

Atoms with the same number of protons but with different numbers of neutrons
Same atomic number as element but different mass number

Question 17

What are ions?

Answer 17

Charged particles
Formed when an atom loses or gains electrons
Can occur during chemical reactions

Question 18

What did Dalton do?

Answer 18

Suggested all matter is made from atoms
- all atoms of an element are identical
- different elements contain different types of atoms

Question 19

What did Thomson do & how?

Answer 19

Found that beams of cathode rays changed direction in electric and magnetic fields
Concluded that cathode rays were tiny negatively charged particles
- atoms contain electrons
- atoms are neutral overall

Question 20

What did Rutherford do?

Answer 20

Tested the plum pudding model in 1909
Pointed beams of alpha particles at thin gold foil
Expected particles to go straight through, most did
Some changed direction and some came back
- atoms have a positively charged nucleus containing most of the mass

Question 21

What did Bohr do?

Answer 21

Electrons occupy shells around the nucleus