There's no fifth element in science as we understand it. The concept of five elements (earth, water, fire, air, and ether) originated in ancient Greek philosophy, not modern science.

In modern chemistry, the elements are defined by their atomic number, which represents the number of protons in their nucleus. We currently know of 118 elements, each with its unique properties.

The five elements of ancient philosophy were an attempt to explain the nature of the universe, but they are not scientifically valid.