An element is anything that has more than one atom. In most chemistry, an atom consists of molecules that contain exactly the same number of protons in their outer atomic nuclei but are unbreakable by chemical forces. The number of protons, together with the number of neutrons, is the only characteristic of an atom and is called the atomic number. There are three kinds of elements; the first type consists of nuclei with a positive charge, and these are hydrogen and helium, while the other types have no nuclei at all and are negatively charged. As mentioned before, it is not possible for matter to be made from the other kinds of elements. It is possible that the hydrogen molecule, containing the only one proton, could break through the neutral barrier to become neutralized and change into one of the other element's molecules, but this is very unlikely. Thus there are four different kinds of elements, although this does not include the sub-atomic particles that make up matter.
Hydrogen and helium atoms are very stable and inert. They do not react to the air around them nor do they react to any of their neighbors, making them a stable element. However, they are very difficult to isolate because of their high density. A gas of this type can be contained within a vacuum chamber and kept at a temperature that is just below absolute zero, but it is also possible to create a gas of this type in a laboratory by forcing a cloud of these clouds of hydrogen and helium atoms together with other molecules.
Carbon atoms are a bit more reactive and are often found mixed with other elements. Although the carbon bonds with another element's electron more readily than the other elements do, carbon is one of the easiest elements to make stable and inert, since its molecular properties are quite simple. Oxygen is very reactive and is a heavy element, which makes it very stable and inert.
