the correct formulae are as follows:

carbon dioxide -CO₂

water- H₂O

element lab game

VERY IMPORTANT  - note that all the numbers are subscript. If your numbers are too large it is wrong.Also note that in compounds containing oxygen, the O is capitalised.  

For the sats question on this topic click here.

What’s the difference between a molecule and an atom?

Atoms are the smallest part of an element. Molecules are two or more atoms joined together. So far so good, but it can be a little confusing, because molecules can be either elements or compounds.

Yesterday we made some models of elements and compounds. Have a look at the phoographs here.

 

Another thing you need to know is how to write the formulae for these molecules correctly – see the next post.
 
test yourself on atoms and elements