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

2. 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

4. 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

5. 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

6. 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.

7. 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.

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