# IB Physics – Topic 3 – Thermal Physics (Core) Sarah Taylor
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Atom

The smallest unit of matter
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Element

A kind of material that is made up of only one type of atom
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Compound

Materials made from molecules that contain more than one type of atom
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A mole of any material contains 6.022*10^23 atoms or molecules
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The three states of matter

Solid, Liquid, Gas
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The physical properties of Solid in terms of molecular structure & particle motion

Fixed shape & volume; Molecule held in position by force, vibrate but don’t move around
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The physical properties of Liquid in terms of molecular structure & particle motion

No fixed shape but fixed volume; Force between molecules not so strong so molecules can move around
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The physical properties of Gas in terms of molecular structure & particle motion

No fixed shaper or volume; No forces between molecules
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Temperature

The intuitive concept of \”hotness\” or \”coldness\” of a substance
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The relation between the Kelvin & Celcius scales of temperature

T(K)=t(C)+273
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Thermal Energy

Energy that is transferred from one body to another as a result of a difference in temperature
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Internal Energy

The total kinetic energy of the molecules of a substance, plus any potential energy associated with forces between the molecules
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The relationship between Internal Energy & Temperature

The average kinetic energy of the molecules of an ideal gas is directly proportional to the absolute temperature of the substance in Kelvin.
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Specific Heat Capacity

The amount of thermal energy required to raise the temperature of one kilogram of one substance by one Kelvin
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Thermal Capacity

The product of the Specific Heat Capacity of a substance & its mass
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The formula involving Specific Heat Capacity

Q=mc*deltaT (Q=Thermal Energy, c=Specfic Heat Capacity)
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How Thermal Equilibrium does occur

When two bodies are in contact, Thermal Energy will be transferred from the hotter body to the colder one until both bodies have the same temperature. This state is called Thermal Equilibrium
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Specific Latent Heat

The amount of thermal energy required to change the state of a substance
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Latent Heat

The product of the Specific Latent Heat of a substance & its mass
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Melting

The process of changing a substance from Solid to Liquid
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Freezing

The process of changing a substance from Liquid to Solid
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Evaporation

The process of changing a substance from Liquid to Gas
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Condensation

The process of changing a substance from Gas to Liquid
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Pressure