Atoms or molecules, whether of a solid, a liquid, or a gas, vibrate. They may also rotate. They may even move through space. This latter form of motion is called translation.
Atoms consist of protons and neutrons in a central core called a nucleus. The nucleus is orbited by one or more electrons. These electrons are called bound electrons, to distinguish them from free moving, unassociated, non-orbiting, electrons.
Atoms + EnergyEnergize atoms and their vibrations, rotations, and translations are almost certain to alter. Exactly what happens depends on the way in which the energy is supplied and the way in which it is absorbed. The greater the atomic or molecular motion, especially of the translational variety, the greater is the heat. The more motion, the hotter the object is.
Temperature: Different from HeatSince some molecules in a system of molecules moves faster or slower than others do, their heat content varies. If we measure the heat average using a device and a scale of comparison, we are said to be taking the temperature of that system. Thus temperature is different from heat. Temperature is a subjective measure of the kinetic energy (energy of the motion) of the system.
Temperature ScalesThere are a number of chemical scales. Some are of great secular value, others are of great scientific value. Scientific scales that are especially relevant to the physical measurement and interpretation of heat include the Kelvin and Rankine scales. These correlate an absolute zero of temperature with the lowest level of atomic and molecular motion.
The Celsius (a.k.a. Centigrade) scale and the Fahrenheit scale are better suited for day to day, use. The Fahrenheit scale is very old. It is especially used in the United States. It is based on two fixed points: 32°F for the freezing point of water, and 212°F being its boiling point. Celsius dictates those two points as 0°C and 100°C, respectively.
- Web Weather for Kids: Temperature and Kinetic Energy
- ThinkQuest: Kinetic Theory of Matter
- University of Florida: Kinetic-Molecular Theory