The elements are identified by its aomic number and they are placed in the periodic table in ascending order of atomic number.
There is one unique element for a given atomic number.
For example, atomic number 1 identifies Hydrogen and there cannot be another different element with the same atomic number.
All the elements with atomic numbers from 1 to 118 have been discovered. So, you know that there is not room for new products with atomic number equal or less than 118.
