The atomic number indicates the number of protons in a given element. It also helps with calculating the weight number to determine if the material in question is an isotope or not (e.g. even though deuterium and tritium are basically isotopes of hydrogen, they may work differently and definitely weigh differently than plain ol' hydrogen).
The number of protons.
The atomic number is the number of protons in an atom of an element.
Atomic number = Number of protons
Atomic number is the number of protons in the atomic nuclei of the atoms of an element.
An element's atomic number is the # of protons in its nucleus.
The atomic number tells you the number of protons in the nucleus of that element.
The atomic number of an element equals the number of protons in the element.
The atomic number of an element refers to the number of protons in the nucleus within the element. This is how the element is identified.
The atomic number of an Element refers to it's position in The Periodic Table. The first element (Hydrogen - H) has the atomic number 1. The second element (Helium - He) has the atomic number 2. The fifty-second element (Tellurium - Te) has the atomic number 52. And so on.
The atomic number is the number fo protons in an atom's nucleus. It decides the element's position on the periodic table, as well as what the element is. No two elements have the same atomic number. As soon as the atomic number, or number of protons, changes, the element itself actually changes into a new element.
The atomic number of an element refers to the number of protons.
The atomic number of an element refers to the number of protons.