States of matter Flashcards

1
Q

describe the structure and movement of solids

A
  • particles are fixed in a regular arrangement forming a regular lattice structure
  • particles are very close together (tightly packed)
  • strong forces of attraction between particles
  • particles vibrate in their fixed positions
  • overall substance keeps a definite shape and volume (can’t flow like a liquid)
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2
Q

describe the structure and movement of liquids

A
  • particles are arranged randomly
  • particles are close together (fairly compact)
  • particles are free to move around in random motion (in all directions) past eachother
  • medium (weak) forces of attraction between particles
  • overall shape can change (can flow to fit a container)
  • liquids have a definite volume
  • particles vibrate around each other
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3
Q

describe the structure and movement of gases

A
  • particles are arranged randomly
  • particles are far apart from eachother
  • particles are free to move around in random motion (in all directions) at high speeds
  • very weak/no forces of attraction between particles
  • gases don’t keep a definite shape or volume
  • gases will always fill a container (spread out as much as possible)
  • gas particles move in straight lines
  • gas particles can be deflected by solid walls or other gas particles randomly
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4
Q

why do solids expand when they are heated?

A

the particles gain more (kinetic) energy and so vibrate more

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5
Q

what are the limitations of the 3D model?

A
  • they are hard to draw
  • they don’t show electrons
  • it can be confusing when there are lots of atoms
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6
Q

what is the particle model (or kinetic model)? Include its assumptions

A

a simple model in which solids, gases and liquids can be represented by lots of particles and it helps us explain how the particles behave in each stage. It assumes that all substances are made from small, solid and inelastic spheres

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7
Q

what is condensation?

A

the process by which a gas turns into a liquid

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8
Q

what is melting?

A

the process by which a solid turns into a liquid

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9
Q

in terms of particles and forces, explain why heating causes a solid to turn into a liquid?

A
  • in solids,strong forces of attraction hold the particles in place so that they can only vibrate in their positions
  • as the substance is heated, the particles gain kinetic energy (absorb thermal energy that is then converted into kinetic energy)
  • they vibrate more often and faster and faster
  • this weakens the forces of attraction between the particles
  • at a certain temperature (melting point), the particles have enough energy to break free of their bonds and the forces holding them together (solid expands until structure breaks)
  • the substance melts into a liquid
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10
Q

which has the highest density - solids, liquids, or gases?

A

solids as the particles are closest together in solids

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11
Q

which theory attempts to explain the three states of matter?

A

particle (kinetic) theory

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12
Q

in terms of particles and forces, explain why heating causes a liquid to turn into a gas?

A
  • as the substance is heated, the particles gain kinetic energy
  • the particles move around faster
  • this weakens the forces of attraction holding the particles together (liquid expands and some particles on the surface gain sufficient energy to overcome the forces of attracton)
  • once we reach the boiling point, particles will have enough energy to break free of their bonds all together and the forces holding them together (all of the particles have enough energy to evaporate)
  • the substance boils or evaporates into a gas
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13
Q

what happens when we heat a gas up?

A
  • when a gas is heated, the particles gain more kinetic energy and move faster
  • the gas will either expand if the container it is in is expandable e.g. a balloon so the volume will increase
  • if the gas is trapped within a container that cannot expand (fixed volume), the pressure inside the container will increase
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14
Q

what happens when we cool a gas down (lower the temperature)?

A
  • in gases, the particles have enough energy to overcome the forces of attraction between them, and so spread out randomly
  • If the temperature is lowered, they will no longer be able to overcome these forces of attraction
  • bonds will start to form between the particles and they will move closer together
  • the gas will condense into a liquid
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15
Q

what is the melting point?

A

the temperature at which a solid turns into a liquid

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16
Q

what is the boiling point?

A

the temperature at which a liquid turns into a gas

17
Q

in a closed system, changes in state won’t change the mass at all. Why is this the case?

A

the number of particles remain the same - a closed system is one in which nothing can get in or out

18
Q

which state has the lowest density?

A

gas

19
Q

what happens when we cool a liquid down (lower the temperature even further)?

A
  • if the temperature is lowered even further, the particles won’t have enough energy to overcome the forces of attraction between them
  • this time even more bonds will start to form fixing the particles in place
  • the liquid will freeze into a solid
20
Q

what are the limitations of the ‘particle theory’ model?

A
  • in reality, the particles aren’t actually small, solid, inelastic or spheres
  • instead they are atoms, ions or molecules
  • the model doesn’t include any details of the forces between the particles
  • it doesn’t consider how strong they are or how many of them there are
21
Q

compare the relative energies of particles in solids, liquids, and gases

A
  • particles in a solid have the least amount of energy (particles are fixed)
  • particles in a gas have the most energy (most spread out)
22
Q

what does ‘interconversion of state’ mean?

A

when matter changes from one state to another due to changes in temperature or pressure

23
Q

what is the name for the state change from liquid to solid?

A

freezing

24
Q

what is the name for the state change from solid to liquid?

A

melting

25
Q

what is the name for the state change from liquid to gas?

A

evaporation

26
Q

what is the name for the state change from gas to liquid?

A

condensation

27
Q

how does a physical change differ from a chemical change?

A
  • a physical change involves changes in the forces between particles - particles themselves remain the same e.g. state changes like melting and freezing
  • a chemical change is different as it affects the chemical properties of the substance so they can change e.g. flammability
28
Q

true of false? ‘Physical changes are relatively easy to reverse’

A

true since no new product is formed during the changes of state

29
Q

what is the term describing when a solid changes straight into a gas?

A

sublimation

30
Q

what happens at the melting point?

A

melting and freezing

31
Q

what happens at the boiling point?

A

boiling (evaporating) and condensing

32
Q

what does the amount of energy needed to to change state from solid to liquid and from liquid to gas depend on?

A

the strength of the forces between the particles of the substance

33
Q

what does the nature of the particles depend on?

A

the type of bonding and the structure of the substance

34
Q

what does it mean if the forces of attraction are stronger between the particles?

A

the higher the melting and boiling point of the subtsance - more energy needed to break apart bonds

35
Q

what state is a substance when it is below the melting point?

A

the substance will be solid

36
Q

what state is a substance when it is above the melting point?

A

the substance will be liquid

37
Q

what state is a substance when it is above the boiling point?

A

the substance will be a gas