Theme B — The Particulate Nature of Matter
B.1.1 Solids, Liquids and Gases — IB Physics HL Revision Notes & Topical Questions
5 min read 10 parts Lesson 3 of 53 1 quiz
Lesson summary
B.1.1 Solids, Liquids and Gases — IB PHYSICS SL notes: Describe the arrangement, motion and forces between particles in solids, liquids and gases and use this to explain their properties.Kinetic theory of matter — a model that explains the three states of matter, treating particl…
- Energy and forces
- Density differences
- Gas pressure
- Changes of state
- Solid keeps its shape
- Liquid flows
Part 1 of 8The particle model
The particle model
Kinetic theory of matter
- Kinetic theory of matter a model that explains the three states of matter, treating particles as small spheres.
Particles
- Particles atoms, molecules or ions that move continually and attract or repel each other.
State
- State it depends on the balance between kinetic energy, which spreads particles out, and intermolecular forces, which hold them together.
Water
- Water ice, liquid water and steam differ only in the arrangement of the particles.
Part 2 of 8Solids
Arrangement
- Arrangement particles are closely packed in a fixed pattern (lattice) with no spaces between them.
- In an amorphous solid such as glass the order is only local.
Motion
- Motion particles vibrate about fixed positions and do not move past each other.
Energy and forces
- Energy and forces they have low energy and cannot overcome the strong forces of attraction holding them together.
Properties
- Properties fixed shape and volume, very difficult to compress and higher density than liquids and gases.
Heating
- Heating the vibrations grow in amplitude and at the melting point break the rigid arrangement.
Part 3 of 8Liquids
Arrangement
- Arrangement particles are closely packed but randomly arranged, with no long-range order.
Motion
- Motion particles vibrate and flow past each other.
Energy and forces
- Energy and forces higher energy than solids, so they partially overcome the intermolecular forces.
Properties
- Properties fixed volume but no fixed shape, difficult to compress, flows easily.
Density
- Density lower than solids but higher than gases;
- water is an exception since ice is less dense than liquid water.
Part 4 of 8Gases
Arrangement
- Arrangement particles are far apart and randomly arranged, with a spacing about 10 times the distance in solids and liquids.
Motion
- Motion particles move in all directions at a variety of speeds, colliding with each other and with the container walls.
Size
- Size the particles are negligible in size compared with the volume of the gas.
Energy and forces
- Energy and forces highest energy, enough to overcome the forces of attraction;
- the forces matter only during collisions.
Properties
- Properties no fixed shape or volume, fills the container, can be compressed and has the lowest density.
Density
- Density about 1000 times smaller than a solid or liquid.
Ideal gas
- Ideal gas a gas with no intermolecular forces and particles of negligible size.
Part 5 of 8Comparison of the states
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Particle arrangement | Fixed pattern (lattice) | Random | Random |
| Space between particles | No space | Some space | Large space |
| Particle movement | Vibrates about a fixed position | Flows past each other | Moves around at different speeds |
| Particle energy | Low | Medium | High |
| Shape | Fixed | Not fixed | Not fixed |
| Volume | Fixed | Fixed | Not fixed |
| Density | High | Medium | Low |
| Compressible | No | Barely | Yes |
Part 6 of 8Macroscopic properties from particle behaviour
Macroscopic properties from particle behaviour
Density differences
- Density differences they come from the spacing of the particles.
Fluids
- Fluids liquids and gases are both fluids because their particles are free to move past each other.
Gas pressure
- Gas pressure each collision exerts an impulse and the vast number per second gives a steady force per unit area.
Changes of state
- Changes of state added energy overcomes the forces between particles and raises potential energy while the temperature stays constant.
Part 7 of 8Explaining in terms of particles
1Pattern
- Pattern state how the particles are arranged, how they move and how strongly they attract, then link to the observation.
2Solid keeps its shape
- Solid keeps its shape its particles are held in fixed positions by strong forces.
3Liquid flows
- Liquid flows its particles slide past one another but stay in contact.
4Diagrams
- Diagrams solids are rows of touching circles, liquids touching circles in random order, gases widely spaced circles with arrows.
5Limits of the model
- Limits of the model glass is amorphous yet solid, and a gas close to condensation shows noticeable intermolecular forces.
Part 8 of 8More from the specification
1
Gravitational compaction of planetary materials
- Gravitational compaction of planetary materials high pressure inside Earth compresses matter into high-density crystalline solids, liquid iron,
- and atmospheric gases.
2
Internal Energy in States of Matter
- The internal energy of a substance is the sum of random kinetic energy and intermolecular potential energy of its constituent particles,
- increasing through solid, liquid,
- and gas phases.
3
Specific Latent Heat of Vaporisation
- The thermal energy required per unit mass to change a substance from liquid to gas at constant boiling temperature, calculated using Q = m * Lv.
4
Modes of Thermal Energy Transfer
- Thermal energy transfers from hotter to cooler regions via particle conduction in solids (such as copper), fluid bulk movement in convection,
- or electromagnetic waves in radiation.
5
Surface Emission and Radiation
- Every object with a temperature above absolute zero emits electromagnetic thermal radiation from its surface, with emission rate governed by the Stefan-Boltzmann law.
6
Wavelength
- Distance between a point on one wave and the same point on the next wave
7
Fusion
- Joining of light nuclei into a heavier one.
8
Intensity
- Power per unit area perpendicular to the wave direction.
9
Apparent brightness
- The power received per unit area at the observer
10
Thermal equilibrium
- Constant temperature because energy is absorbed and lost at equal rates
11
Phase change
- Change of matter from one state to another
12
Thermal conductivity
- Material constant relating the rate of conduction to the temperature gradient and area
13
Surface temperature
- Effective temperature of the star's radiating surface.
14
Thermal
- A convection current in the air.
15
Radiation
- Transfer by electromagnetic waves, requiring no medium
16
Copper
- Metal widely used for electrical wires.
17
Convection
- Transfer of thermal energy by the movement of a heated fluid
18
Conduction
- Transfer of thermal energy by lattice vibrations and free electrons
19
Luminosity
- The total power of radiation emitted by a star.
20
Capacity
- Charge a cell can supply, in A h or C.
Key terms
| Term | Meaning |
|---|---|
| Kinetic theory of matter | Model explaining the properties of matter in terms of moving particles |
| Lattice | Regular repeating arrangement of particles in a crystalline solid |
| Intermolecular force | Force of attraction between particles |
| Fluid | A liquid or a gas, able to flow |
| Amorphous solid | Solid with only local order, such as glass |
| Ideal gas | Gas with no intermolecular forces and negligible particle size |
Avoid these mistakes
1
Saying solid particles do not move — they vibrate about fixed positions.
2
Saying gas particles are bigger or heavier than liquid particles — only the spacing and energy differ.
3
Drawing gas particles close together — they are far apart.
4
Saying liquids have no forces between particles — the forces are weaker than in solids but significant.
5
Saying water is as dense as ice — ice is less dense than liquid water.
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