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Question 1

What (and when) did Dalton propose about atoms?

Answer 1

everything was made of indivisible tiny spheres called atoms in 1800

Question 2

What key discovery did JJ Thomson make in 18XX?

Answer 2

1897 - He discovered the electron and proposed the Plum Pudding Model.

Question 3

What did the Plum Pudding Model suggest?

Answer 3

Atoms are a sphere of positive charge with negative electrons dispersed within it. - cancel out charges

Question 4

What experiment did Rutherford conduct in 1911?

Answer 4

The Gold Foil Experiment (carried out by Geiger and Marsden).

Question 5

What did Rutherford’s experiment reveal about atomic structure?

Answer 5

most alpha particles went straight through - atom mainly empty space
some slightly deflected - nucleus must be +, hence repelling other + charges
Few particles deflected >90 - nucleus has most mass in atom

Question 6

What was the Bohr model in 1913?

Answer 6

Electrons exist in orbitals (shells) - doesn’t get attracted to + nucleus otherwise atom would collapse

Question 7

What subatomic particles are found in the nucleus of an atom?

Answer 7

Protons and neutrons.

Question 8

What are the relative mass and charge of a proton?

Answer 8

Mass = 1, Charge = +1.

Question 9

What are the relative mass and charge of a neutron?

Answer 9

Mass = 1, Charge = 0.

Question 10

What are the relative mass and charge of an electron?

Answer 10

Mass ≈ 0.0005 Charge = -1.

Question 11

Where are electrons found in an atom?

Answer 11

In energy levels (orbitals/shells) at different distances from the nucleus.

Question 12

How big is a typical atom?

Answer 12

About 1 × 10⁻¹⁰ metres.

Question 13

Where is most of an atom’s mass concentrated?

Answer 13

In the nucleus.

Question 14

What is the definition of density?

Answer 14

Mass per unit volume.

Question 15

What is the formula for density?

Answer 15

ρ = m / V (density = mass / volume)

Question 16

What are the units of density?

Answer 16

kg/m³ or kgm^-3

Question 17

What does density depend on?

Answer 17

The spacing of the atoms in matter.

Question 18

Why do solids and liquids generally have higher densities than gases?

Answer 18

Because the space between particles in solids and liquids is small. - more particles in the same volume than gas

Question 19

Why do gases have lower densities?

Answer 19

Gas particles are far apart and have high energy, occupying a larger volume. - less particles in a given volume

Question 20

What is an exception where a solid is less dense than a liquid?

Answer 20

Ice is less dense than water.

Question 21

What happens to mass during a change of state?

Answer 21

It is conserved (remains the same).

Question 22

Do changes of state affect the density of a substance?

Answer 22

Yes, because the volume changes.

Question 23

Are changes of state physical or chemical?

Answer 23

Physical – they are reversible and retain the material’s properties.

Question 24

What is the difference between heat and temperature?

Answer 24

Temperature = average kinetic energy of particles (measured on a relative scale);

Heat = energy (measured on an absolute scale).

Question 25

What are the two outcomes when a substance gains heat energy?

Answer 25

1. It raises in temperature but stays in the same state. 2. It changes state but stays at the same temperature.

Question 26

What is specific heat capacity (c)?

Answer 26

The energy needed to raise the temperature of 1 kg of a substance by 1ºC (or 1K)

Question 27

What is the formula for heat energy with specific heat capacity?

Answer 27

E = m × c × ∆T

Question 28

What are the units for specific heat capacity?

Answer 28

J/kg°C

Question 29

What is specific latent heat (l)?

Answer 29

The energy needed to change the state of 1 kg of a substance without temperature change.

Question 30

What is the formula for energy with latent heat?

Answer 30

E = m × l

Question 31

What are the units for specific latent heat?

Answer 31

J/kg or Jkg^-1

Question 32

What is specific latent heat of fusion (or melting)?

Answer 32

energy transferred when 1kg of substance changes from solid to liquid state or visa versa

Question 33

What is specific latent heat of vaporisation?

Answer 33

energy transferred when 1kg of substance changes from liquid to gas state

Question 34

How do particles move in a fluid?

Answer 34

They move randomly in all directions.

Question 35

What are fluids?

Answer 35

Liquids or gases.

Question 36

What is the formula for pressure?

Answer 36

Pressure = Force / Area (p = F / A) Pressure measures in pascals Pa

Question 37

In which direction does pressure produce a net force?

Answer 37

At right angles to any surface.

Question 38

What happens to pressure when temperature increases (at constant volume)?

Answer 38

Pressure increases.

Question 39

Why does increasing temperature increase pressure in a fluid?

Answer 39

Particles gain kinetic energy, move faster, and collide more frequently and forcefully with container walls. - closed system only

Question 40

What is the proportional relationship between pressure and temperature (at constant volume)?

Answer 40

Pressure ∝ Temperature (p ∝ T)

Question 41

What happens to a gas when pressure changes?

Answer 41

gas is compressed or expanded

Question 42

How are volume and pressure related (at constant temperature)?

Answer 42

They are inversely proportional. (p ∝ 1/V)

Question 43

What happens to pressure if volume increases?

Answer 43

Pressure decreases, because collisions occur less frequently per unit area.

Question 44

What happens to pressure if volume decreases?

Answer 44

Pressure increases, because particles collide more often with each other and the container in a smaller space.

Question 45

How are temperature and volume related (at constant pressure)?

Answer 45

They are directly proportional. (V ∝ T)

Question 46

What happens to volume as temperature increases (at constant pressure)?

Answer 46

Volume increases to maintain constant pressure.

Question 47

What happens to a fluid’s temperature when work is done on it?

Answer 47

The temperature increases. - such as a bicycle pump

Question 48

What is the formula for work done involving pressure and volume?

Answer 48

Work done = Pressure × Volume (W = p × V)

Question 49

How can pressure increase by adding more gas?

Answer 49

More particles cause more collisions, transferring energy and raising temperature.

Question 50

How can reducing volume heat a fluid?

Answer 50

Particles collide more frequently, increasing pressure and kinetic energy, thus increasing temperature.

Question 51

What assumption is made about Earth’s atmospheric temperature?

Answer 51

It is assumed to be isothermal (same temperature throughout).

Question 52

How does the atmosphere interact with solar and terrestrial radiation?

Answer 52

It is transparent to solar radiation but opaque to terrestrial radiation.

Question 53

What assumption is made about atmospheric density?

Answer 53

It is assumed to be uniform density.

Question 54

What is atmospheric pressure?

Answer 54

The total weight of the air above a unit area at a given altitude.

Question 55

What happens to atmospheric pressure as altitude increases?

Answer 55

It decreases, because there are fewer air molecules above

Question 56

Why does a helium balloon expand as it rises?

Answer 56

Lower external pressure means the helium inside exerts more force, causing expansion.

Question 57

When does the expansion of a balloon stop?

Answer 57

When internal and external pressures reach equilibrium (usually it bursts before this).

Question 58

When does an object float in a fluid?

Answer 58

When its weight is less than the weight of fluid it displaces.

Question 59

What happens if an object’s weight is more than the displaced fluid?

Answer 59

It sinks.

Question 60

What must happen for a 1000kg boat to float?

Answer 60

It must displace 1000kg of water before fully submerging.

Question 61

What causes pressure in a liquid to vary?

Answer 61

Depth and density of the liquid.

Question 62

What is the upward force on an object in a liquid called?

Answer 62

Upthrust (Buoyancy force) – it counteracts the object’s weight.

Question 63

Why does a ping pong ball float?

Answer 63

Its density is less than water, so it displaces enough water to balance its weight.

Question 64

Why does pressure increase with water depth?

Answer 64

The weight of the water column above increases.

Question 65

What is the formula for pressure due to a liquid column?

Answer 65

p = h × ρ × g (pressure = height × density × gravitational field strength)

Question 66

What is the value of g (gravitational field strength) used in calculations?

Answer 66

10 N/kg

Question 67

Why is upthrust created?

Answer 67

Pressure increases with depth So pressure at bottom of object is greater than pressure at the top The difference in pressure creates a net upward force - upthrust

Question 68

For an object to float, what does the upthrust need to be equal to?

Answer 68

Needs go be equal to weight of object

Question 69

Upthrust equation

Answer 69

Upthrust = force from bottom - force from top = (pressure x area at bottom) - (pressure x area at top) = weight of object (if floating in equilibrium)