Chapter 4 - Elements, Mixtures and Compounds Section 2 – Compounds (pp. 94-97)

COMPOUNDS Definition: A compound is a pure substance composed of two or more elements that are chemically combined. Examples of compounds: Water Carbon dioxide Sugar

COMPOUNDS A compound is a new pure substance that is different from the elements that reacted to form it. and forms A white solid that is safe to eat A soft, silvery metal Poisonous yellow gas

Compounds Pure substance composed of two or more different elements joined by chemical bonds. Made of elements in a specific ratio that is always the same Has a chemical formula Can only be separated by chemical means, not physically H2O NaCl CO2

Each compound has a unique set of properties Each compound has a unique set of properties. The properties of a compound are different from the properties of the elements that formed it.

COMPOUNDS Compounds can be broken down into simpler substances by chemical changes. They cannot be broken down by physical changes. Some compounds are first broken down into smaller compounds, then broken down into elements by additional chemical changes.

WAYS TO BREAK DOWN A COMPOUND Heating 2. Electrolysis – passing an electric current through it

COMPOUNDS IN YOUR WORLD There are compounds found in nature. These include proteins and carbon dioxide. Compounds found in industry include ammonia (used in fertilizer) and other compounds used in medicines, food preservatives and synthetic fabrics.