Ms. Messina’s Science Class Temperature Ms. Messina’s Science Class

Temperature A measure of the thermal energy in an object A measurement of the average kinetic energy of the particles in a sample (how fast molecules are vibrating) The three temperature scales are Celsius, Kelvin, and Fahrenheit

What temperature really is Atoms are in constant motion, even in a solid object. The back-and-forth jiggling of atoms is caused by thermal energy, which is a kind of kinetic energy.

Thermometer An instrument used for measuring temperature

How a thermometer works The volume of alcohol in a thermometer contains huge numbers of alcohol molecules. As temperature increases, the alcohol molecules move faster and bounce off each other. The liquid alcohol expands and takes up more space in the thermometer.

Celsius Most commonly used by scientists throughout the world Water freezes at 0 degrees and boils at 100 degrees on the Celsius Scale

Kelvin This is the metric unit (SI) of temperature 0 degree K is coldest possible temperature (-273 degree Celsius) Absolute Zero Kelvin uses the same scale as Celsius Water freezes @ 273 degree and boils at 373 degrees Kelvin

Fahrenheit Used in the United States Water freezes at 32 degree and boils at 212 degrees Fahrenheit Different Scale than C and K

Important Concepts As temperature rises the molecules in an object begin to move faster As temperature decreases, the molecules move slower

Temperature and Density As molecules move faster (temp. rises), they take up more space (volume increases) As volume increases density decreases So the opposite I true, as temperature decreases the volume decreases and density increases

Converting to Kelvin The Kelvin temperature scale is useful in science because it starts at absolute zero. To convert from Celsius to Kelvin, you add 273 to the temperature in Celsius.

Absolute zero Absolute zero is -273°C. You cannot have a temperature lower than absolute zero. Think of absolute zero as the temperature at which atoms are “frozen.”

What temperature really is Temperature measures the kinetic energy per molecule due to random motion.