When a metal is heated, its atoms begin to vibrate more vigorously and move further apart from each other. This increases the distance between the atoms, which in turn causes the metal to expand and become longer.
The amount of expansion that a metal undergoes when heated depends on several factors, including the type of metal, the initial temperature of the metal, and the rate at which it is heated. In general, most metals will expand by a small amount when heated over a wide range of temperatures.
At very high temperatures, some metals may begin to undergo a phase change, such as melting or vaporization. This can cause the metal to undergo a significant change in length, depending on the amount of phase change that occurs.
Overall, the length of a metal will generally increase as the temperature increases, although the exact amount of expansion will depend on the specific conditions and the type of metal involved.