What is atomic number and what relationships does it have to the periodic table?

Atomic number is the number of protons in the nucleus of an atom. All of the atoms of the same element have the same number of protons, and therefore the same atomic number. For example, all hydrogen atoms have one proton in their nuclei, and hydrogen's atomic number is 1; and all carbon atoms have six protons in their nuclei, and carbon's atomic number is 6. Each element's identity is determined by its atomic number. The relationship between the Periodic Table and atomic number is that the elements are arranged in the periodic table according to increasing atomic number, starting with hydrogen and ending with Ununoctium, which has an atomic number of 118.