Atomic Number:

According to current atomic theory, every proton in the universe is precisely like every other. The neutrons are all similar too. The number of protons in an element's nucleus, the atomic number, provides that element its identity.

The element with three protons is lithium, a light metal which reacts easily by gases like chlorine or oxygen. Lithium forever has three protons; in opposition, any element with three protons in its nucleus should be lithium. The element with four protons is beryllium, which is also a metal. Carbon has six protons, nitrogen has seven, and oxygen has eight in its nucleus. In common, as the number of protons in an element's nucleus rises, the number of neutrons also increases. The elements with high atomic numbers, like lead, are consequently much denser than elements with low atomic numbers, like carbon. Possibly you have compared a lead shot with a piece of coal of same size and observed this difference.

If you could in some way add two protons to the nucleus of each atom in a sample of carbon, you would end up with an equivalent number of atoms of oxygen. Though, this is much simpler said than done, even with a single atom. It is likely to change one element into the other; the Sun does it all time, fusing the hydrogen into helium. The procedure is far from trivial, however. In ancient times, alchemists tried to do this; the most familiar illustration of their pursuits was the quest to turn lead (atomic number 82) into gold (atomic number 79). As far as anyone knows, they never succeed. It was not until the year 1940s, whenever the first atomic bombs were tested, that elements really were "morphed" by human beings. The outcomes were quite different from anything the alchemists ever attempted for.

The table shown below lists all the known elements.