As scientists gained a better understanding of the structure of matter, they realized that some of the early explanations about the nature of heat needed to be modified. Heat was no longer thought to be made up of a fluid called caloric. Matter was now thought to ber composed of small building blocks called atoms, which could be combined different ways to make larger units called molecules. Any new concept of heat must take into account the molecular nature of matter. Most scientists agreed that these molecules must be in motion relative to each other. This motion could be considered kinetic energy, or energy of motion.

Thanks to the work of scientists like Boyle, Charles, and Gay-Lussac, it became clear that what we call heat was dependent upon the amount of motion in the molecules of a substance. Given a fixed amount of matter, the more the molecules moved, the more heat was contained within the substance.

Through the use of statistics, it was determined that in a given group of molecules, there would be a distribution of molecular speeds from relatively slow to relatively fast, Most of the molecules would have speeds close to the average for the group. The kinetic energy of this average speed is know as temperature.

It was observed that when the temperature increased, the graph of the molecular speeds shifted to the right. This means that more molecules have a higher kinetic energy than before the temperature rise. Higher kinetic energy allows chemical reactions to take place more quickly.

While the new kinetic theory of heat explained many things, it only worked in perfect situations, and at lower temperatures. Scientists then set up an artificial condition called a black body to better help predict the analysis of heat and kinetic energy of much hotter objects, like stars. A blackbody would absorb all radiation hitting it, so any light given off would be from its temperature.

Higher temperatures resulted in radiation of higher frequency, or shorter wavelength. To see what effect a rise in temperature would have on color, click the lowest right scroll arrow below. To see a drop in temperature, click the lowest left arrow.

----- COOLER || HOTTER -----

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