Topic 14/15 particle model Flashcards
What are the features of a solid, including:
Closeness of particles
Arrangement of particles
Movement of particles
Energy of particles
Very close
Regular lattice pattern/structure
Vibrate around a fixed position
Low energy
What are the features of a liquid, including:
Closeness of particles
Arrangement of particles
Movement of particles
Energy of particles
Close
Randomly arranged
Move around each other
Greater energy
What are the features of a gas, including:
Closeness of particles
Arrangement of particles
Movement of particles
Energy of particles
Far apart
Randomly arranged
Move quickly in all/random directions
Highest energy
Recall and use the equation:
Density =
density (kilogram per cubic metre, kg/m3) = mass (kilogram, kg) ÷ volume (cubic metre, m3)
p = m/V
How do you find the density of a liquid
measure the mass of rocks on a balance
Get a measuring cylinder and record a small volume of water
Gently put rocks/object in to prevent water spillage
Record new volume
Do the new volume - old volume to get the volume of the object
use that volume with the mass and do p = m/V to get density
repeat with all other objects (IF THERE ARE OTHERS)
Explain the differences in density between the different states
of matter in terms of the arrangements of the atoms or
molecules
in a solid – particles are tightly packed in a regular structure. in a liquid – particles are tightly packed but free to move past each other. in a gas – particles are spread out and move randomly.
Describe that when substances melt, freeze, evaporate, boil,
condense or sublimate mass is ________ and that these
physical changes differ from some chemical changes because
the material _________________________ if the change is
reversed
conserved
recovers its original properties
Explain how heating a system will change the energy stored
within the system and raise its temperature or produce
changes of state
Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state.
Define the terms specific heat capacity and specific latent heat
and explain the differences between them
SHC: It is the energy needed to raise the temperature of
1kg of a material by 1oC. It is measured in J/kg oC
SLH: Energy is required to break all the intermolecular bond between molecules. The temperature remains constant until the state changes.
specific heat capacity relates to temperature changes within a state, while specific latent heat relates to state changes at a constant temperature.
Use the equation:
change in thermal energy (joule, J) =
mass (kilogram, kg) × specific heat capacity (joule per kilogram degree Celsius, J/kg °C) × change in temperature (degree Celsius, °C)
∆Q = m * c * ∆θ
thermal energy for a change of state (joule , J) =
mass (kilogram, kg) × specific latent heat (joule per kilogram, J/kg)
Q = m * L
Explain ways of reducing unwanted energy transfer through thermal insulation
To reduce the amount of energy that is transferred to the surroundings by heating, the object needs to be surrounded with insulating materials such as:
- wool
- foam
- bubble wrap
It prevents any more thermal energy from being transferred.
Explain the pressure of a gas in terms of the motion of its
particles
Gas particles collide with the surface of the container
Particles exert a force
P = F/a so higher force means higher pressure
Explain the effect of changing the temperature of a gas on the
velocity of its particles and hence on the pressure produced by
a fixed mass of gas at constant volume (qualitative only)
Increasing the temperature of a gas at constant volume causes its particles to move faster, leading to more frequent and forceful collisions with the container walls, thus increasing the pressure
Describe the term absolute zero, ____°C, in terms of…
-273
The lack of movement of particles
Convert between the kelvin and Celsius scales
temperature in degrees Celsius (°C) = temperature in Kelvin - 273
temperature in Kelvin = temperature in degrees Celsius (°C) + 273
Explain that gases can be compressed or expanded by
pressure changes
Compression:
When pressure is applied to a gas, the gas particles are forced into a smaller volume. This means that there are fewer particles within that space, and they collide with the container walls more frequently. This increased frequency of collisions results in a higher pressure.
Expansion:
When pressure is reduced on a gas, the gas particles can move further apart. This increases the volume of the gas, and the particles collide with the container walls less frequently. This decreased frequency of collisions results in a lower pressure.
Boyle’s Law:
The relationship between pressure and volume in a gas is described by Boyle’s Law, which states that for a fixed amount of gas at a constant temperature, the pressure and volume are inversely proportional. This means that if you increase the pressure, the volume decreases, and vice versa
Use the equation:
to calculate pressure or volume for gases of fixed mass at
constant temperature
P1 * V1 = P2 * V2
Explain, using springs and other elastic objects, that stretching, bending or compressing an object requires more
than one force
To stretch, bend, or compress an object, you need to apply more than one force.
This is because if only one force acts, the object will simply move (translate), rather than change shape.
To change the shape of an object (like stretching a spring), at least two forces must act in opposite directions.
Spring (Stretching):
You need to pull at both ends of the spring.
One force pulls left, one pulls right → this causes stretching, not movement.
Describe the difference between elastic and inelastic distortion
Elastic distortion is when an object returns to its original shape after the force is removed.
Inelastic distortion is when the object does not return to its original shape — it is permanently deformed.
Elastic distortion happens when the limit of proportionality or elastic limit has not been exceeded.
Inelastic distortion happens when the object is stretched or compressed beyond that point.
Recall and use the equation for linear elastic distortion
including calculating the spring constant:
force exerted on a spring (newton, N) = spring constant
(newton per metre, N/m) × extension (metre, m)
F = kx
Use the equation to calculate the work done in stretching a
spring:
energy transferred in stretching (joules, J) = 0.5 × spring
constant (newton per metre, N/m) × (extension (metre, m))2
E = 1/2 k x^2
Describe the difference between linear and non-linear
relationships between force and extension
Linear Relationship:
Force and extension are directly proportional — when you double the force, the extension also doubles.
This follows Hooke’s Law:
F= kx
Where F is force, k is the spring constant and x is the extension
The graph of force vs extension is a straight line through the origin.
✅ Non-linear Relationship:
Happens when the force is too great and the object is stretched beyond its limit of proportionality.
The extension no longer increases in proportion to force — the graph curves.
The spring may undergo inelastic distortion and not return to its original shape.
Core Practical: Investigate the extension and work done when
applying forces to a spring
Secure a clamp stand to the bench using a G-clamp or a large mass on the base.
Use bosses to attach two clamps to the clamp stand.
Attach the spring to the top clamp and a ruler to the bottom clamp.
Adjust the ruler so that it is vertical and with its zero level with the top of the spring.
Measure and record the unloaded length of the spring.
Hang a 100 g slotted mass carrier - weight 0.98 newtons (N) - from the spring. Measure and record the new length of the spring.
Add a 100 g slotted mass to the carrier. Measure and record the new length of the spring.
Repeat step 7 until you have added a total of 1,000 g.
What does the graph for hookes law look like
y = x but with a hook going up at the end
Explain why atmospheric pressure varies with height above
the Earth’s surface with reference to a simple model of the
Earth’s atmosphere
As you go higher up, there is less air above you.
So the weight of air above decreases, and therefore the atmospheric pressure decreases.
Air is also less dense at higher altitudes (particles are more spread out), so there are fewer collisions, which also lowers pressure.
Describe the pressure in a fluid as being due to
the fluid and atmospheric pressure
Explain how pressure is related to force and area, using
appropriate examples
P = F/A
High heel shoes: Small surface area = high pressure = can sink into soft ground.
Snowshoes: Large surface area = lower pressure = prevents sinking into snow.
Recall that the pressure in fluids
causes a force normal to any surface
Recall and use the equation:
pressure (pascal, Pa) =
force normal to surface (newton, N) ÷ area of surface (square metre, m2)
Describe how pressure in fluids increases with depth and density
The deeper you go in a fluid, the more weight of fluid is above you, so pressure increases.
Denser fluids have more mass in the same volume, so they exert more pressure at the same depth.
Explain why the pressure in liquids varies with density
and depth
Pressure in a liquid depends on how deep you are and how dense the liquid is.
A greater depth = more fluid above = higher pressure.
A greater density = more particles in each volume = greater weight of fluid = higher pressure.
Use the equation to calculate the magnitude of the pressure in liquids and calculate the differences in pressure at different depths in a liquid:
pressure due to a column of liquid (pascal, Pa) =
height of column (metre, m) × density of liquid (kilogram per cubic metre, kg/m3) × gravitational field strength (newton per kilogram, N/kg)
P = hpg
Explain why an object in a fluid is subject to an upwards force (upthrust) and relate this to examples including objects that are fully immersed in a fluid (liquid or gas) or partially immersed in a liquid
Upthrust is an upward force acting on an object in a fluid.
✅ Why it happens:
Pressure increases with depth in a fluid.
The bottom of the object is at a greater depth, so experiences a greater pressure than the top.
This difference in pressure creates a net upward force = upthrust.
✅ Examples:
A submarine experiences upthrust when fully underwater.
Recall that the upthrust is equal to
the weight of fluid displaced
Explain how the factors (upthrust, weight, density of fluid) influence whether an object will float or sink
If upthrust > weight: Object rises
If upthrust = weight: Object floats (equilibrium)
If upthrust < weight: Object sinks
(THE NEXT BIT ISNT NEEDED BUT CAN BE USED)
✅ What affects upthrust:
The volume of fluid displaced — bigger objects displace more fluid = more upthrust.
The density of the fluid — denser fluids provide more upthrust for the same volume.
✅ So:
An object will float if it can displace enough fluid to create an upthrust equal to its weight.
If an object is less dense than the fluid, it floats (like wood in water or helium in air).
If it is more dense, it sinks.
