When matter is heated, the kinetic energy of its particles increases. Temperature is a measure of the average kinetic energy of the particles in a substance. As heat is added to the matter, it causes the particles—atoms and molecules—to move more rapidly. This increased motion can manifest in several ways depending on the state of the matter:
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Solids: In solids, particles are held in fixed positions by intermolecular forces, but when heated, they vibrate more vigorously around their fixed positions. The increased vibration energy contributes to an increase in the overall kinetic energy of the particles.
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Liquids: In liquids, the particles have more freedom to move compared to solids. When heated, the increase in kinetic energy causes the particles to move faster and may also lead to increased interactions between them, which can eventually result in a change of state (for example, boiling).
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Gases: In gases, particles are much farther apart and move freely. When the gas is heated, the particles move more rapidly, leading to a significant increase in kinetic energy. This rapid movement can cause the gas to expand and exert more pressure against the walls of its container.
Overall, the increase in temperature corresponds to an increase in the average kinetic energy of the particles within the matter being heated.