Physical and Chemical Changes (Reactions)

Matter and Particles Matter is everything in the universe that has mass and takes up space Matter includes things we can easily observe Matter also includes things not easily seen

Particles are so small they can only be seen with the strongest microscopes.

Particles are arranged to form the states of matter: Solids Liquids Gases

Solids have a definite shape take up a definite amount of space Particles are very close together.

Liquids take the shape of its container take up a definite amount of space Particles slip and slide around each other.

Gases have no definite shape take up no definite amount of space always fill the container it is in Particles do not stay close together. They move around very fast.

Physical Changes A physical change is any change in the size, shape, or state of a substance

Physical changes produce a change in size, shape, or state. Most physical reactions are reversible. You can change it back to its original form.

Physical changes can be caused by a change in temperature. water boiling and turning into steam

Physical changes can be caused by motion. wool being spun into thread

Physical changes are caused by pressure. powerful pressure machines flatten steel into sheet metal

Chemical Changes A chemical change is a change that produces one or more new substances and may release energy.

Chemical changes produce a change in odor, color, or create energy. Chemical changes are not reversible.

An example of a chemical change is baking brownies. Eggs, flour, oil, water, and cocoa are stirred together then heated to a high temperature. When done, you end up with something very different than the parts you put in.

Identify the picture as a chemical or physical change.