When a metal (such as copper) is heated, itexpands. Explain what happens to the metalparticles as the solid metal expands.

When a metal like copper is heated, it expands due to the increase in kinetic energy of its particles. Here's a step-by-step explanation:

1. Heating the metal provides energy to the particles (atoms, ions or molecules) that make up the metal.

2. This energy increases the kinetic energy of the particles, causing them to vibrate more vigorously.

3. As the particles vibrate more, they move further apart from each other. This is because the increased kinetic energy overcomes the forces of attraction between the particles, allowing them to move into new positions further away from each other.

4. This increase in distance between the particles results in an increase in the volume of the metal - in other words, the metal expands.

5. Once the heat source is removed and the metal cools down, the particles lose kinetic energy, the vibrational motion decreases, and the particles move closer together again, causing the metal to contract.

So, the expansion of a heated metal is due to the increased movement and spacing of its particles.