The notations that represent chemical elements are known as chemical symbols. Using a symbol made up of two letters instead of complete names to refer to elements in chemistry simplifies things. It's a short-hand method based on how we use short names in our everyday lives to depict better chemical processes in science pictures.
Atoms, their internal structures, and their subatomic particles are represented by atomic symbols. Let's start with the subatomic particles that make up the atom. We now have a better knowledge of atoms and their inner particles thanks to modern atomic theory. A nucleus made up of neutrons and positively charged protons makes up an atom. Electrons reside in a large region outside the nucleus of an atom.