particle model of matter

  • Created by: ellie_225
  • Created on: 19-05-18 19:41
density =
mass/volume
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units for density
kilograms per meter cubed - kg/m3
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units for mass
kilograms, kg
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units for volume
meters cubed - m3
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what does the particle model explain
different states of matter and differences in density
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is mass conserved when change of state
yes
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changes of state
physical changes - the material recovers to its original properties
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what does the density of an object depend on
the material it is made from
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1ml is the same as
1cm3
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1m3
10000cm3
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measuring regular density
find mass - calculate volume
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measuring irregular density
find mass - record volume of water + object then see how much more volume
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displacement can
measure overflowing water
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soild particles
vibrate about fixed positions within a close packed regular structure. particles cannot move in between each other which results in a solid having a definite shape and fixed volume..
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solid density
high density because the particles are closely packed together.
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the particles in a liquid
move in-between each other and are approximately the same distance apart as in a solid.
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shape of a liquid
• does not have a definite shape but it does have a fixed volume.
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density of liquid
quite high density because the particles are close together. The density of a liquid decreases if it heats up because the particles spread out. This means they occupy a larger volume for the same mass.
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particles in a gas
move in-between each other and are much further apart than they are in a liquid.
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shape of gas
takes up the shape and volume of its container.
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density of gas
low density because the particles are spread far apart. The density of a gas decreases if the gas heats up because the particles spread out. This means they occupy a larger volume for the same mass.
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internal energy
Energy is stored inside a system by the particles (atoms and molecules) that make up the system.• Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.
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how does heat change the energy stored
increases the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state.
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internal energy definition
energy stored by the particles
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particles have
• kinetic energy, because they are moving, and • potential energy due to the position of the particles
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internal energy
kinetic energy + potential energy
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if a change of state happens
• The energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature.
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energy for a change of state =
mass x specific latent heat
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units
energy, E, in joules, J mass, m, in kilograms, kg specific latent heat, L, in joules per kilogram, J/kg
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specific latent heat of fusion
change of state from solid to liquid
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specific latent heat of vaporisation
changes of state from liquid to vapour
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melting or fusion
solid is heated, the particles gain energy and vibrate more. energy is added to allow the particles to break away. The solid has melted Energy is needed to break from the forces of attraction they gain potential energy as the bonds are broken
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melting or fusion 2
The temperature of the material does not rise although energy is added to it, because the kinetic energy of the particles does not change. This energy is called the latent heat of fusion
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evaporation
liquid is heated - particles gain energy - move more - some of the particles gain enough energy to break away from the liquid - they have evaporated - energy allows particles to break away from liquid is called latent heat of vaporisation
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latent heat
the energy needed for a substance to change state without changing temperature.
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specific latent heat
is the energy needed to change the state of 1kg of the substance.
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energy =
mass x latent heat
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investigating latent heat
Measure the time that the heater is on - Total energy = power of heater x time Measure mass of melted water and subtract the mass of the control Latent heat of fusion = energy / mass
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if the temp of the system increases it is because of ...
increase in temperature depends on the mass of the substance heated, the type of material and the energy input to the system.
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change in thermal energy =
mass x specific heat capacity x temperature change
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units for change in thermal energy
change in thermal energy, ΔE, in joules, J mass, m, in kilograms, kg specific heat capacity, c, in joules per kg per degree Celsius, J/kg °C temperature change, Δθ, in degrees Celsius, °C.
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the specific heat capacity of a substance is
the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
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when an object is heated, the change in its temp depends on three things
Mass of the object Change in temperature Material it is made from
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is the specific heat the same for different materials
no it is different in every material
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what is specific heat a measure for
how food the material is at soaking up the energy
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specific heat of water
4200 J/kg / oC
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specific heat of iron
390 J/kg / oC
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the higher the thermal conductivity of a material
the higher the rate of energy transfer by conduction across the material
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do warm objects emit infa red
yes
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the hotter the object
the more infra red it will radiate
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are Dark, matt surfaces are good emitters of infra red.
yes and Dark objects will cool down more quickly.
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what are bad emitters of radiation
light and shiny surfaces
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what surface will cool the quickest
if a hot object is cooling an object with a shiny surface will cool down more slowly than a black one. These foil blankets stop marathon runners cooling down too quickly when they have finished the race.
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what are good absorbers and what are bad absorbers
dark, matt surfaces are good absorbers of infra red - light, shiny surfaces are bad absorbers; they reflect the infra red rays - therefore black things will heat up more quickly
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examples of infra red radiation
¥ In hot weather we prefer to wear light coloured clothes. Black clothes make us heat up too much in the sun. ¥ Thermos flasks have a shiny surface inside. This helps to keep the drink warm by reflecting infra red rays back into the drink.
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what way does thermal energy travel
¥ Thermal energy (heat) always travels from hotter objects to colder ones.
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how is energy made in solids
In solids, the particles are very close together. When they heat up, they vibrate more vigorously. ¥ These vibrating particles collide with the particles next to them and make them move more. In this way energy is passed along the object.
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roof insulation
¥ Fibreglass insulation helps to keep a house warm, by reducing the heat lost through the roof. It has a low U value.
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saucepan conduction
¥ The handle is made of an insulating material - plastic or wood ¥ The pan is made of a conducting material - metal ¥ Thermal energy travels through the water by convection.
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convection - what happens to the particles
The particles in liquids and gases are free to move and so can carry thermal energy from one place to another.
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convection - what cannot happen
Convection cannot occur in solids because the particles cannot move
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convection - what happens
The water near the Bunsen burner heats up and so becomes less dense. It rises, and cooler, more dense, water sinks to take its place. The resulting circulation is called a convection current.
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convection in a kettle
¥ The heating element is at the bottom. The water near it heats up and rises and colder water sinks to take its place. All the water in the kettle gets warm.
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keeping house warm
¥ Roof - Fibre glass insulation ¥ Walls - Cavity wall insulation§
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molecules and temperature of gas
The molecules of a gas are in constant random motion. The temperature of the gas is related to the average kinetic energy of the molecules.
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what changes the pressure of gas
Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas.
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can gases be compressed
A gas can be compressed or expanded by pressure changes. The pressure produces a net force at right angles to the wall of the gas container (or any surface).
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what happens when you increases the volume
• increasing the volume in which a gas is contained, at constant temperature, can lead to a decrease in pressure.
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for a fixed mass of gas held at a constant temperature
constant = pressure x volume
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units for pressure
pressure, p, in pascals, Pa
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units for volume
volume, V, in metres cubed, m3
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gases particles dont move true/false
The particles in a gas are constantly moving.
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is the motion of gas particles random
Their motion is completely random. This random motion can be demonstrated by observing smoke particles – Brownian motion.
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how is the temperature related to kinetic energy
The temperature of a gas is directly related to the average kinetic energy of the particles. Kinetic energy, Ek = ½ mv2, so the hotter the gas, the faster the particles move.
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the particle theory of gas explains gas pressure 1
gas molecules move in random motion, when a molecule collides w/ a surface it exerts a force on the surface as it changes its direction
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particle theory of gas 2
The pressure exerted by the gas is equal to the total force exerted by the molecules over an area of the surface divided by the area. [P = F/A] The net force, and therefore the pressure is at right angles to the surface.
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what happens when you increase the volume of a container
Increasing the volume of the container that the gas is in, means that the gas particles collide with the sides of the container less often and the pressure is lower.
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boyles law
states that the pressure of a gas is inversely proportional to its volume. This means that if the volume of a gas is doubled its pressure will halve.
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when is boyles law applied
only applies for a gas if its mass and temperature is kept constant while the volume is being changed.
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boyles law equation
p1 x V1 = p2 x V2
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gas pressure and temperature
If a gas is heated up, in a fixed volume, the pressure will increase. • When the gas particles get hotter, they move faster. This means that they collide with the walls of the container more frequently, so the pressure increases.
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fixed volume
increasing the temperature increases the pressure
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fixed pressure
decreasing the volume increases the temperature
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fixed temp
decreasing the volume increases the pressure
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increasing the pressure of a gas
Work is the transfer of energy by a force. Doing work on a gas increases the internal energy of the gas and can cause an increase in the temperature of the gas.
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work done =
force x distance moved in the direction of the force
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work done = energy transformed
• Work done = energy transferred • If work is done on a gas, energy is transferred to it.
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units for density

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kilograms per meter cubed - kg/m3

Card 3

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units for mass

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Card 4

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units for volume

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Card 5

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what does the particle model explain

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