P1 - Matter

Question 1

What was Dalton’s Model?

Answer 1

He thought that an atom was a very small indestructible sphere, he thought:

• all atoms in an element are the same
• The atoms in one element are different from all the atoms in another element

Question 2

What was Thompson’s model?

Answer 2

Thompson used cathode rays are made of particles that have a negative charge which he named an electron. He then came up with the plum-pudding model, a positive mass with negatively charged electrons embedded inside it.

He also thought atoms were neutral overall

Question 3

What was Rutherford’s model?

Answer 3

Rutherford using his gold foil experiment suggested that:

• an atom is mostly empty space
• has a tiny positively charged nucleus
• electrons around the outside

Question 4

How did Rutherford come up with his idea for the model of an atom?

Answer 4

Gold foil experiment with Geiger and Marsden:

• fired positively charged alpha particles at a thin sheet of gold foil
• most went through suggesting an atom is mostly empty space
• some bounced back suggesting a positively charged nucleus

Question 5

What is density?

Answer 5

Density is the amount of mass in a certain volume

Density = mass / volume

Question 6

Why is the density of a substance in the solid state greater than the same substance in the liquid state?

Answer 6

There are more particles packed together in the same volume for a solid as the particles are closer together, this means there is a higher mass which means a higher density

Question 7

What is the law of conservation of mass?

Answer 7

You have to add or remove material for the mass of a system to change, particles do not appear or disappear

Question 8

What is the difference between energy and temperature?

Answer 8

• The energy in a thermal store is measured in Joules, depends on how the particles are arranged and how fast they are vibrating
• Temperature tells you the average kinetic energy of a particle

Question 9

What is specific heat capacity?

Answer 9

The amount of energy needed to raise the temperature of 1kg of a substance by 1K.

• change in thermal energy (J) = Mass(kg) * Specific heat capacity* Change in temperature

Question 10

What is latent heat?

Answer 10

• The specific latent heat for fusion is the energy transferred when 1kg of a substance changes from the solid to liquid state
• The specific latent heat for vaporisation is the energy transferred when 1kg of a substance changed

Question 11

Why do gas particles exert pressure?

Answer 11

• As gas particles move around they bang against each other or container
• When they collide with something they produce a small force
• All these collisions produce an overall net force against a container
• This is pressure

Question 12

How does temperature affect pressure?

Answer 12

• If the temperature of a gas increases
• The particles have a higher average speed
• They collide more frequently with the sides of a container
• These collisions produce a bigger force over a certain area
• This produces a bigger pressure

Question 13

How are pressure and volume related?

Answer 13

They are inversely proportional:

• If the pressure halves, the volume doubles
• If the pressure doubles, the volume halves

At a constant temperature :
- Pressure * Volume = Constant

Question 14

How does doing work on a gas affect temperature?

Answer 14

For example a bike pump:

• If you apply a force to the pump and move it
• average speed of particles increase because their kinetic energy increases as they collide with the moving piston
• Therefore increasing temperature

Question 15

Explain why a weather balloon expands as it rises:

Answer 15

• As the balloon rises atmospheric pressure decreases
• Therefore the pressure inside the balloon will be greater than the pressure outside
• This results in a higher volume as there is a bigger force pushing outwards inside the balloon to try make the pressures equal

Question 16

What happens to atmospheric pressure as you go up?

Answer 16

Pressure decreases as:

• higher up there are less particles pushing down on top of you
• density is therefore lower higher up
• temperature is also lower higher up

Question 17

What is liquid pressure?

Answer 17

Water exerts a liquid pressure that acts in all directions due to the particles of the liquid

It increases with depth

Pressure due to a column of liquid(Pa) = depth(m) * density of liquid * g

Question 18

What is upthrust?

Answer 18

• The force that is pushing upwards when you are in water
• It is equal to the water displaced when floating

If upthrust < less than weight, the object will sink

An object will float if it’s less dense than the liquid that it’s trying to float in