Atomic Number and Mass Number

The atomic number is the number of protons in the nucleus. The overall charge of an atom is zero. This is because an atom has the same number of electrons as protons.The number of protons in the atom of an element is unique and identifies the element. There are about 114 elements and therefore 114 different types of atom. The atomic number of an element is the number of protons in the nucleus. The atomic number is different for each element and identifies the element.The periodic table lists the elements in order of atomic number.
The mass number is the number of protons and neutrons in the nucleus.