Thermal energy 7 TH GRADE SCIENCE
Temperature There s more to temperature than the idea of hot and cold. Remember that all matter is made up of tiny particles that are constantly moving even in solid objects. Because they are moving, these particles have kinetic energy.
Temperature Temperature is a measurement of the average kinetic energy of the particles in matter. As something is heated, its particles will move faster. This means that their kinetic energy is higher and therefore their temperature will go up. Cold Hot
Temperature scales There are three scales for temperature. Fahrenheit Celsius Kelvin The difference between these are how much thermal energy each unit measures and where they start.
Daniel Gabriel Fahrenheit Temperature scales Fahrenheit has the smallest unit. 0 is the coldest the scientist who invented it could get salt water and 100 is about human body temperature.
Anders Celsius Temperature scales Celsius has larger units, almost twice the size of Fahrenheit. 0 is the freezing point of water and 100 the boiling point of water.
Temperature scales Kelvin has units the same size as Celsius. 0 Kelvin is the temperature known as absolute zero. William Thomson, Lord Kelvin
Absolute zero As the temperature of matter decreases the speed of its particles decrease. At some point the particles will stop moving. Absolute zero is the lowest possible temperature. Where particles stop moving and matter contains no thermal energy.
Thermal energy Thermal energy is the total energy of the particles in an object and depends on the temperature of the object.
Thermal energy constantly wants to even out with everything around it. Heat is the movement of thermal energy from a warmer object to a cooler object.
Specific heat Not every object heats up or cools down at the same rate. Different chemicals require different amounts of heat to change temperature. Specific heat is the amount of energy needed to raise the temperature of 1 kilogram of something 1 kelvin.
Specific heat Something with a high specific heat can absorb a large amount of thermal energy without changing its temperature very much.
Transferring heat Heat always flows from warmer objects to colder ones. As the temperature of one object increases the temperature of the other will decrease. Some materials transfer thermal energy better than others.
Conductors A conductor transfers thermal energy very well. Metals are good conductors. Good conductors feel cool when you touch them because they transfer heat away from your skin.
Insulators An insulator does NOT transfer thermal energy very well. Wood, wool, paper, and air are good insulators. Insulation prevents thermal energy from moving from one place to another very well.
States of matter A state is a form of matter. Matter can exist in three different states. Solid, liquid, or gas.
Solids An object s state of matter depends on how much thermal energy it has. Solids the particles of a solid cannot move out of their positions, they can only vibrate back and forth.
Liquids Liquids the particles in a liquid are close together, but they are not held in place like in solids so they can move around more. Therefore liquids don t have a shape.
Gasses Gasses the particles in a gas are moving so fast that they don t stay close together, they expand apart to fill the space they are in. They don t have a fixed shape or volume.
States of matter
Changes of state The change from one state of matter to another is called a change of state. A change of state happens when thermal energy is absorbed or released.
Changes of state Melting when a solid turns into a liquid. Freezing when a liquid turns into a solid. Evaporation/boiling When a liquid turns into a gas.
Changes of state Condensation when a gas turns into a liquid. Sublimation when a solid turns into a gas without first becoming a liquid.
Thermal expansion Thermal expansion is when matter spreads out and expands when it is heated.