Elements.

class of atoms with the same number of protons (nuclear charges) in a nucleus is called an element. There are currently 109 known elements, 16 of which are non-metallic, 6 are rare gases and 87 are metal. Everything in the universe is made up of atoms or molecules or ions of these elements. There are now more than 10 million known substances. Most elements contain different numbers of nucleuts in their nucleus. For example, there are three types of oxygen elements (16O, 17O, and 18O), which contain 8, 9, and 10 nucleos in the nucleus of their atoms, respectively. These three oxygen elements are called the three nucleotins of oxygen, and they are
each other
. The first chemist to give the element the first scientific definition was Boyle. In 1661, he wrote in The Doubt chemist: "The element I am referring to should be something primitive and simple or completely pure that is not made up of any other substance." ""Elements are certain, tangible, imperceptible objects that should no longer be broken down into simpler objects by general chemical methods." From a modern point of view, Boyle's definition actually refers to monotony.