Simple english c01/History
Before 1600, people studied substances to figure out how to do things such as turn lead into gold, but no one managed to do that. This was called alchemy. Alchemists (people that did alchemy) did discover some useful things, though. Sulphuric acid and nitric acid were two substances that they discovered. Only a few elements were known. Some of them are mercury, silver, gold, and carbon.
Chemistry began as a true science during the 1600s. This is when chemists discovered the simplest substances that make up all other substances. These simple substances are called elements. One of the things that they learned is that gold and lead are made of two different elements, so you can not change one into the other by a chemical reaction. The first element discovered after 1600 was phosphorus, a strange white glowing solid.
Elements were discovered more and more rapidly. People separated the air into many parts and isolated the noble gases from it. They also processed special minerals from a mine in Sweden to get rare earth metals. Radioactivity was also discovered. Today chemists have discovered 118 different elements. Some are very common, like oxygen. Many are very rare and expensive, like platinum. Some cannot be found on earth and can only be made in labs, like rutherfordium.
Since the 1920s, the increased understanding of physics has changed chemists' theories about chemical reactions. With smaller and faster computers, chemists have built better tools for analyzing substances. These tools have been sent to study chemicals on Mars. Police also use those tools to study evidence from crime