Metalwork - Materials - Compounds

A Compound is defined as a pure substance where 2 or more different Atoms are chemically combined. A Compound has its own properties which are totally different from the properties of the Atoms which make it up and from any other Compound. It is also important to note that the ratio of the Atoms in a compound cannot be changed. If it is then you have a new Compound. A Compound can only be destroyed or broken up into its parts by chemical means. You can tell what atoms make up a Compound by looking at its Chemical Formulae. We can take water as an example. Water's chemical formulae is H2O. This means that water is made up of 1 part Oxygen and 2 parts Hydrogen. If you compare the properties of Water, Oxygen and Hydrogen you will see that they are totally different. You can breath Oxygen but try breathing water! A Molecule is the basic part of a Compound. When you cannot break a substance down any more without changing its properties you have found the Molecule of the Compound. Have fun trying to do that at home! Below are some common Compounds that you might know.

Compound Formulae
Water H2O
Salt NaCl
Carbon Dioxide CO2
Carbon Monoxide CO
Sugar C6H12O6
Hydrochloric Acid HCl
Sulfuric Acid H2O4
Nitric Acid HNO3
Sodium Hydroxide NaOH
Iron Sulfide FeS
Some common Compounds

Compounds can also be shown by the use of simple diagrams. Below on the left you can see a diagram of a water Molecule, and on the right is a diagram of a sugar Molecule. You could count the Atoms, and you will find that your result will be the same as the the information in the table above. When you look at the sugar Molecule you will notice that it seems to be all over the place. Well it's not, what you see is the way the Atoms join together. If you want to know more about how and why Atoms join together look at Chemical Bonds. And to help you a little, C is for a Carbon Atom, O is for an Oxygen Atom and H is for a Hydrogen Atom.

A Water Molecule
A Sugar Molecule