Particle Model Of Matter

Question 1

Where is most of the mass of an atom found?

Answer 1

In the nucleus

Question 2

Who discovered the nucleus?

Answer 2

Ernest Rutherford

Question 3

How did Rutherford discover the nucleus?

Answer 3

He fired a beam of alpha particles at thin metal foils (only a few atoms wide)

Most alpha particles passed through the foil. This suggested that most of the atom is made up of empty space. However some particles bounced back towards the source.

Question 4

What was Rutherfords conclusions of his experiment?

Answer 4

• The large deflections suggested that some positively charged mass in the atom was repelling the particles.
• This led to the model of the atom with negatively charged electrons orbiting a positively charged nucleus.

Question 5

Why would alpha particles be deflected by a smaller angle if the thin metal foil was made of a lighter element?

Answer 5

The nuclei of lighter elements contain fewer protons. This means that they have a lower charge. Each alpha particles will, therefore, experience a smaller electric force acting on it and so deflect by a smaller angle.

Question 6

What is J.J Thomson discover?

Answer 6

Electrons

Question 7

What is the ‘plum pudding’ model?

Answer 7

J.J Thomson described the atom as a ‘plum pudding’ which was a ball of positive charge with negatively charged electrons mixed in.

Question 8

What did Niels Bohr discover?

Answer 8

That electrons orbit the nucleus at fixed distances

Question 9

What did James Chadwick discover?

Answer 9

He discovered that the same particles in the nucleus have no charge at all. He called them neutrons.

Question 10

What is absorb radiation?

Answer 10

When atoms absorb electromagnetic radiation, electrons move to a higher energy level further away from the nucleus.

Question 11

What is emit radiation?

Answer 11

When atoms emit electromagnetic radiation, electrons can drop to a lower energy level, closer to the nucleus.

Question 12

What is the equation for density?

Answer 12

ρ = m ÷ v

Density = mass ÷ volume

Question 13

What is upthrust?

Answer 13

Upthrust is when an object’s density is lower than the density of the fluid (floats).

Question 14

What is law of displacement?

Answer 14

The Law of Displacement says that an object completely submerged in a fluid will replace an amount of fluid equal to its own volume.

Question 15

From most dense to least dense, order the states of matter.

Answer 15

Solid
Liquid
Gas

Question 16

Why are changes of state not a chemical reaction?

Answer 16

Because the material recovers its opd properties if the change is reversed.

If the change was chemical, then it would be irreversible. The material would not be able to return to its original properties.

Question 17

What is conservation of mass?

Answer 17

When a substance changes state, its mass is conserved.

Question 18

What type of change is a change of state?

Answer 18

Physical

Question 19

What are the properties of the changes of state?

Answer 19

1) Mass is converted
2) Reversible
3) Physical process

Question 20

What are the standard units of density?

Answer 20

kg/m³

Question 21

The amount of energy in an object’s internal store is the sum of what?

Answer 21

Of kinetic and chemical potential stores of the object’s particles.

Question 22

Where does energy in an object’s potential store come from?

Answer 22

The energy in an object’s potential comes from the potential energy in the bonds between particles?

Question 23

What is specific heat capacity?

Answer 23

The specific heat capacity of a substance is the amount of energy needed to increase the temperature of 1kg of that substance by 1°C.

Question 24

What is the equation for thermal capacity?

Answer 24

Thermal capacity = mass x specific heat capacity

Question 25

A glass jar has a metal lid that's difficult to unscrew. Why does holding the jar under a hot tap help to open the lid?

Answer 25

The metal expands at a greater rate than the glass for the same temperature increase and this loosens the lid.

Question 26

What is a Leslie cube?

Answer 26

Leslie's cube is a metal box with 4 different colour sides (black, matte black, white, unpainted).

Question 27

How do you use a Leslie cube?

Answer 27

If you pour hot water into the cube, the matte black side will emit more infra-red radiation than the other sides. The infra-red radiation emitted is measured using a thermopile.

Question 28

What is latent heat?

Answer 28

Latent heat is the energy that is transferred to a substance without the substance's temperature changing.

Question 29

Why isn't latent heat measured?

Answer 29

If we measure energy using the change in temperature, this energy transfer will not be measured. The energy is transferred without the temperature changing.

Question 30

What is specific latent heat?

Answer 30

Specific latent heat is the latent heat per 1kg of mass. It is a way to standardise across objects that have different masses.

Question 31

Where does latent heat go when a substance changed state?

Answer 31

When a substance changes state, this energy is absorbed to create or weaken bonds, rather than transfer kinetic energy to a substance's particles.

Question 32

What happens to the energy supplied during a change of state at both the melting and boiling points?

Answer 32

Kinetic energy remains constant while the potential energy increases.

Question 33

What is the equation for energy change for change of state?

Answer 33

Energy = mass x specific latent heat

Question 34

What is latent heat of vaporisation?

Answer 34

The latent heat of vaporisation is the amount of energy needed to covert a liquid into a gas without changing the substance's temperature.