Today, we learned what some of those pure substances are:
Some elements exist as atoms, while some exist as molecules. The elements are all found on the Periodic Table, which has their special symbol.
Compounds are formed when different elements react. This means they join together chemically, forming bonds between the atoms. Compounds can be molecules (like some elements) or they can be ionic. We learn more about these in the next few years of Science and Chemistry...
Our task today was to classify all matter from what we have learned in the last few weeks and in today's lesson.