Matter and Energy

Energy The capacity to do some kind of work, such as moving an object, forming a new compound, or generating light.

Physical Change Affects only the physical properties of matter. E.g.-when ice melts or water turns to steam

Chemical Change Occurs whenever a new substance is made Like when the gases hydrogen and oxygen make water

Changes in Matter Every change in matter involves a change in energy. Evaporation occurs when enough energy is absorbed by a liquid that it becomes a gas.

Endothermic reaction Describes a process in which heat is absorbed from the environment. Example-like when alcohol evaporates and feels cool.

Exothermic reaction Describes the process in which a system releases heat into the environment. For instance Thermacare pads

Law of Conservation of Energy The law that states that energy cannot be created or destroyed but can be changed from one form to another. Like photosynthesis-which changes light energy into sugar energy

Heat The energy transferred between objects that are at different temperatures. Energy is always transferred from objects of higher temperatures. Like when warm air touches your skin

Kinetic Energy The energy of an object that is due to the object’s motion. Like a car speeding down the highway.

Temperature A measure of how hot or how cold something is. Can be measured by the Fahrenheit, Celsius or Kelvin scale.

Specific Heat The quantity of heat required to raise a unit mass of homogeneous material 1g of a substance 1 degree Kelvin in a specified way given constant pressure and volume. Expressed in joules per gram Kelvin (J/gK)

Scientific Method The procedures used as a strategy for drawing sound or true conclusions. A guideline for solving problems in science.

Hypothesis A proposed explanation for an observation A reasonable and testable explanation for a problem or question An educated guess

Theory Any hypothesis that withstands repeated testing A well-tested explanation for an observation

Law A statement or mathematical expression that reliably describes the cause of certain events in the natural world Describes events