Particle Model of Matter Flashcards
What can be used to explain the different states of matter and their properties?
Kinetic theory
In solids, what are the forces like & what do they do?
Strong forces of attraction hold particles close together in fixed, regular arrangement
In solids, how much energy does particles have and what does this mean?
Particles don’t have much energy = only vibrate about their fixed positions
In solids, what is the density like and why?
Highest density = particles are closest together
What are the forces like in liquids?
Weaker forces of attraction between particles
What’s the arrangement like in liquids?
Particles are close together but can move past each other = form irregular arrangements
In liquids, how much energy does particles have and what does this mean?
Have more energy than solids = particles move in random directions at low speeds
In liquids, what is the density like?
Less dense than solids
What are the forces like in gas?
Almost no forces of attraction between particles
In gases, how much energy does particles have and what does this mean?
Have more energy (than in liquids + solids) = particles free to move & travel in random directions at high speeds
In gases, what is the density like?
Low - less dense than liquids
Draw the arrangement of particles in a solid
Draw the arrangement of particles in a liquid
Draw the arrangement of particles in a gas
A Change of State _______ ____
Conserves Mass
Internal energy is stored by the _____ that makes up a ____
the Particles that makes up a System
When does a change in state occur?
If substance heated enough = particles will have enough energy in their kinetic energy stores to break bonds holding them together
What is latent heat?
Energy needed to change state of substance
When substance is melting or boiling, what are you doing essentially?
Putting in energy = increasing internal energy
When a substance is melting or boiling, what is the internal energy used for?
Used for breaking intermolecular bonds rather than raising temperature
What do flat spots on heating graph represent?
Where energy is being transferred by heating but not being used to change temperature
When a substance is condensing or freezing, how is energy released?
Bonds are forming between particles = which releases energy
When a substance is condensing or freezing (bonds are forming between particles), what does this mean for internal energy and temperature?
Means internal energy decreases BUT temperature doesn’t go down until all substance has turned to liquid or solid
Draw a heating graph
Draw a cooling graph
What is specific latent heat?
Amount of energy needed to change 1 kg of a substance from one state to another without changing its temperature
For cooling, SLH is energy _____ by a change in state
released
What is latent heat of fusion?
Amount of energy needed to change the state of 1 kilogram of a substance from a solid to a liquid with no change in temperature
What is latent heat of vaporisation?
Amount of energy needed to change the state of 1 kilogram of a substance from a liquid to a vapour with no change in temperature
What does impurities affect?
Melting point of solid & boiling point of liquid
What is specific heat capacity?
Amount of energy needed to raise the temperature of 1kg of a substance by 1°C
Greater mass of object = …
more slowly temperature increases when heated
Energy may be transferred by _____ and _____
evaporation and condensation
What does the rate at which an object transfers energy by heating depends on? (name 3 things)
- Material of object
- Its surface area and volume
- Nature of the surface with which the object is in contact
Bigger the temperature difference between an object and its surroundings = …
faster the rate at which energy is transferred by heating
Most substances _____ when heated
expand
When does evaporation happen?
When a liquid turns into a gas below its boiling point
What is the cooling of a liquid by evaporation caused by?
Faster-moving particles escaping from the liquid
How can evaporation be increased? (name 3 ways)
- Increasing SA of liquid
- Increasing temp. of liquid
- Creating a draught of air across liquid’s surface
When does condensation happen?
When a gas turns into a liquid
How can condensation on a surface be increased? (name 2 ways)
- Increasing area of surface
- Reducing temperature of the surface
What do cooling fins on motorcycle engine do?
Find increase SA of engine in contact with air = engine transfers energy to surroundings faster
Gases expand on heating much ____ than solids and liquids
more
Expansion of substances on heating can be a ____ or _____
hazard or useful
How do bimetallic strips work?
- Consists of 2 different metals (e.g. brass and steel) bonded together
- When temp. of strip increases = one metal expands more than other (e.g. brass more than steel) = so strip bends
- Used to switch on or off an electrical device
Where are expansion gaps needed?
In buildings, bridges, railways tracks
Why are expansion gaps needed in bridges?
Temperature changes = expansion of bridge = bridge would buckle
