F1 C6 6.3 Compounds

A compound is formed when two different elements or more reacted CHEMICALLY.

Examples are:
 $Magnesium\ +\ Oxygen\ \ \rightarrow\ Magnesium\ Oxide$   $Iron\ +\ Oxygen\ \rightarrow\ Iron\ Oxide$  

Magnesium, zinc, iron and copper react with oxygen to form the metal oxide.

There are some metals that react with water to form alkali compounds and release hydrogen gas. These elements are known as alkali metals. Examples of alkali metals are lithium, sodium and potassium.

Examples are:

Physical change does not form a new substance.

Example:

Ice melting, water freezing, water boiling

Chemical change forms a new substance that is different from the original substance.

Example:

Rusting of iron nail, photosynthesis, decaying of leaf and cell respiration