Most of the things around us are combinations because if they were all pure elements then some would be very haazradous and could take the lives of many people like radium the rays of radium and any other radioactive elements like X rays they are actually bad for you but they arent as harful as any other rays. Uranium is one of the elements that can tell us if there are any rays. Other elements like magnesium is very thin and flammable, and magniesieum is harmful is consumed sometimes it is used in medicine and if that medicine is taken way to much then the person consuming it would have stomache cramps and facial ticks and have a risk of death. And water is not an elements water is a molecule, made of 2 hydrogen and one oxygen. Carbon dioxide is an element.....I think but it is made of carbon and 2 oxygens. I hope this brings out the idea that most elements around us are actually made of several elements so its a combination (molecule). Hope this helps. :)