Chapter 6

 All matter is made up of atoms or molecules.  These particles are constantly in motion. The energy of motion is called kinetic energy.  Temperature is the measure of the average Kinetic Energy of the individual particles in a substance.

 Whenever something becomes warmer, the kinetic energy of its atoms or molecules has increased. The temperature of the hot liquid has increased.

 Particles in the cold chocolate milk are moving slower than the hot chocolate and the particles have a lower temperature or kinetic energy.

 A thermometer is used for measuring temperature.  As the liquid in the thermometer becomes warmer, the molecules move faster and further apart, and the liquid in the tube rises.  As the liquid cools, the molecules move slowly and the liquid contracts in the tube.

 The 3 most common scales for measuring temperature are the Fahrenheit, Celsius, and Kelvin Scales

 The temperature scale used commonly in the United States is the Fahrenheit scale.  The number 32 is the temperature at which water freezes.  The number 212 is the temperature at which water boils  The interval between these two temperatures is divided between 180 equal intervals called degrees Fahrenheit

 The most widely used temperature scale in the world is the Celsius scale.  The number 0 is the temperature at which water freezes.  The number 100 is the temperature at which water boils.  The interval between freezing and boiling is divided into 100 equal parts, called degrees Celsius.

 The temperature scale used in Physical Science is the Kelvin Scale.  Units on the Kelvin Scale are the same size as the Celsius Scale and are called kelvins (K)  Freezing Point of water on the Kelvin Scale is 273 K and the Boiling Point is 373 K

 Scientists believe that -273 degrees Celsius or 0 degrees Kelvin is the lowest temperature possible.  At this temperature no more energy can be removed from the matter.  This temperature has not truly been reached.

 The total energy of all the particles in a substance is called the Thermal Energy or Internal Energy  If two samples of matter have the same temperature does not mean that they have the same Energy.

 The more particles a substance has at the given temperature the more the more thermal energy it has  The water in the bucket has greater Thermal energy than the cup of water at the same temperature. Thermal Energy is the measure of the energy of all the particles.

 What is the relationship between the temperatures of a substance and the speed of its molecules?

 The higher the temperature of a substance, the faster is the motion of its molecules

 Power point Compiled by Mrs. Lal for 8 Z Students  Text Book “ Science Explorer” by Prentice Hall