Compounds and Elements 2.5 +2.8 summary

Now we all know that pure substances is made up of only one kind of matter and has a unique set of properties, such as; color, hardness, boiling point and melting point.

So, for example: If you were to add sand with water then its no longer a pure substance. The property changes and so does the mixture.

A pure substance is

• either an element or a compound.

Example:  Carbon [ C ] is an element and sugar [ NaCl ] is a compound.

Electrolysis is the production of a chemical reaction by means of an electric current.

Here's a video showing the electrolysis of water.

MORE facts about elements.

• it cannot broken down / decompose
• there are 109 elements
• it can exist as a solid, liquid, or gas
• can exist as an individual or as larger units
• have different melting and boiling points

Molecules 

• made of more than one atom