There are obviously quite a few CC members who didn't pay attention in their school science classes so here is a little refresher course for you -
pay attention at the back!
Elements are the purest substances in nature. The smallest amount of an element that you can get is an
Atom. Atoms are actually made of sub-atomic gubbins (
Electrons,
Protons,
Neutrons...) but as far as the 'real world' is concerned you can forget about that stuff and just let the physicists worry about it.
Many substances are
Compounds consisting of
Molecules created by chemical reactions between atoms. In planet Earth conditions, some elements don't actually seem to like existing as individual atoms. The atoms in the elements Hydrogen and Oxygen for example tend to go around in pairs. Those elements also have a great affinity for each other so if they are mixed together, at the slightest excuse (a lighted match will do!) they will undergo a chemical reaction (also known as a very loud bang!). The result will be molecules of water.
Hundreds of years ago, people used to think that you could transmute one element into another if you went about it the right way. Actually, they were right because if you happened to have a man-made nuclear reactor or a natural one like a star handy you could do just that. Mixing a few powders together, adding essence of frog and reciting a few magic verses doesn't do the trick though so the old Alchemists were doomed to failure when they tried to make Gold that way.
Gold is an example of an element that is pretty antisocial. It is quite happy to hang about by itself under normal circumstances rather than reacting with all and sundry. It is possible to form compounds between gold and other elements but it takes a bit of effort.
Gold belongs to the family of elements known as
Metals. Not all metals are as antisocial as gold. Iron, for example is by comparison the life and soul of the party! Add iron to water and air and before you know it you have a good rust thing going on. Some metals are a bit too friendly though - the aforementioned Potassium being a notable example. Those who didn't fall asleep in their chemistry classes will vividly remember what happened when teacher mister Jones dropped a pellet of potassium into a beaker of water. His safety glasses and the straw bales surrounding the beaker were good clues that something interesting was about to happen! Yes, it undergoes a really violent reaction - you don't use a hose on a potassium fire! Fortunately, the potassium in your bananas (or spuds!) has already reacted with other elements to form relatively stable compounds. This is why you don't explode when you eat a banana sandwich. If you see somebody about to bite into a potassium sandwich, stand clear, insert earplugs and wear an offal-proof gown!
PS I've just read that in the entire history of mankind the total amount of gold discovered on Earth is only about 160,000 tons - amazing, eh!