As thermal energy is added to a system, the particles within that system typically experience an increase in kinetic energy. This can lead to several observable changes in the behavior and arrangement of the particles, depending on the state of the matter (solid, liquid, or gas) and the amount of energy added:
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In Solids:
- The particles vibrate more vigorously around their fixed positions as thermal energy increases.
- At a certain temperature, known as the melting point, they gain enough energy to overcome some of the forces holding them in place, allowing the solid to change to a liquid.
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In Liquids:
- As thermal energy is further added, the kinetic energy of the liquid particles increases, resulting in faster movement.
- When enough energy is added, the liquid reaches its boiling point and undergoes a phase transition to become a gas. In this phase, the particles have enough energy to break away from the attractions of neighboring particles, leading to a more dispersed arrangement.
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In Gases:
- In a gas, particles already move freely, but adding thermal energy increases their speed and the distance between them.
- This can lead to an increase in pressure if the gas is contained, or if the gas is expanding, it may occupy a larger volume.
In summary, adding thermal energy to a system generally results in an increase in particle motion and can lead to phase changes depending on the amount of energy and the state of the substance.