Physical and Chemical Changes

Physical change- changes the form of an object without changing what type of matter it is.

Sublimation- change of state directly from a solid to a gas.

Just before freezing, water molecules move farther apart and line up in a solid arrangement.

Expands and pushes on a cup

Boiling point- water’s boiling point is 100 degrees celsius

Thermal expansion-the increase in an object’s volume due to change in heat.

Thermal contraction-the decrease in an object’s volume due to a change in heat.

Ice is less dense than water. So water expands, instead of contracts, when it freezes

This joint keeps the bridge from breaking or buckling on hot days

Mixture- a physical combination of substances. The substances remain the same.

Colloid- a mixture like a suspension, except that its parts do not settle. The particles are just small enough not to layer out.

Mayonnaise, foam- examples of colloids

Solution- mixture with parts that blend so that it looks the same everywhere.

Example: sugar into water, bleach

Solute- substance that is dissolved (sugar)

Compound- formed by the combination of two or more elements.

Iron Oxide= 2 iron atoms and 3 oxygen atoms

Chemical Reaction- atoms link to create a new substance. Example- baking soda, vinegar.

Chemical Equations- left side is the chemicals that combine (reactants). Right side is the new substance (product).

Total mass is equal

Plants- create food using photosynthesis ( a chemical reaction), simple sugars

Acids- dissolve in water, taste sour, turn blue litmus to red, help digest food, used to clean steel and plastics.

Base- turns red litmus paper blue, can clear clogged drains, used to make fertilizers, used to make cloth, soaps, and some plastics.

Neutralization- when acids and bases react to form salt and water.

Electrolyte- a substance that forms ions in water.

Found in sports drinks