Temperature: definition in chemistry
Temperature: A measure of how hot or cold something is, related to the average kinetic energy of its particles.
When a substance is heated, its particles move faster and its temperature rises. Scientists use the Kelvin scale, which starts at absolute zero (0 K, or −273.15 °C), so a value in kelvins is the Celsius value plus 273.15, and gas law calculations must use kelvins. Temperature is not the same as heat: a warm bath holds more heat energy than a cup of boiling water, even though its temperature is lower.
Examples
- Water freezes at 0 °C (273.15 K) and boils at 100 °C at sea level
- Normal human body temperature is about 37 °C
- Absolute zero — 0 K, or −273.15 °C
- Liquid nitrogen boils at about −196 °C (77 K)
On the periodic table
Many tables color-code elements as solid, liquid or gas at room temperature (about 25 °C): only mercury and bromine are liquids, while gallium and cesium melt just above it.