A change in thermal energy directly influences the movement and arrangement of particles within a substance. Here is how this works for solids, liquids, and gases:
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Solids: In solids, particles are closely packed together in a fixed arrangement and can only vibrate in place. When thermal energy increases (such as heating), these vibrations become more intense, causing the particles to vibrate more vigorously. If the thermal energy is sufficiently increased (like reaching the melting point), it can overcome the forces holding the particles in fixed positions, causing the solid to melt into a liquid.
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Liquids: In liquids, particles are still in close proximity but are not in a fixed arrangement, allowing them to slide past one another. An increase in thermal energy leads to greater movement among the particles, which increases the liquid's temperature and can eventually lead to boiling if sufficient energy is added. At this boiling point, the liquid transitions to a gas as the particles gain enough energy to break free from the intermolecular attractions holding them together.
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Gases: In gases, particles are far apart and move freely at high speeds. An increase in thermal energy further enhances this movement, resulting in higher kinetic energy. As a result, gas particles collide with each other and the walls of their container more frequently and with greater force. If enough thermal energy is added, it can lead to changes in pressure or volume, or even to ionization in extreme conditions.
Overall, as thermal energy changes within a substance, there is a corresponding change in the kinetic energy and arrangement of its particles, which can lead to phase changes (solid, liquid, gas) and alterations in properties like temperature, pressure, and volume.