Learn what atomic number is, how to find it, and why it is important for identifying elements. See the list of atomic numbers and symbols of all 118 elements in the periodic table.

Learn the definitions, facts, examples and calculations of atomic number and mass number, the two whole numbers that identify an atom. Find out how they are related to protons, neutrons, electrons and isotopes.

Atomic number, the number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. Accordingly, the number of protons, which is always equal to the number of electrons in a neutral atom, is also the atomic number.

The atomic number is simply the number of protons in an atom. For this reason, it's sometimes called the proton number. In calculations, it is denoted by the capital letter Z. The symbol Z comes from the German word zahl, which means number of numeral, or atomzahl, a more modern word which means atomic number.

Find the atomic number, symbol, and name of 118 elements in the periodic table. Learn about the future elements and their temporary names.

The atomic number (represented by the letter Z) of an element is the number of protons in the nucleus of each atom of that element. An atom can be classified as a particular element based solely on its atomic number.

Fundamental properties of atoms including atomic number and atomic mass. The atomic number is the number of protons in an atom, and isotopes have the same atomic number but differ in the number of neutrons.

The atomic number of a sodium atom is 11 and its mass number is 23. Calculate the number of protons, neutrons and electrons it contains.

Learn what atomic number is, how it relates to the subatomic structure of elements, and how it organizes the periodic table. Explore the history of atomic number as a theory and a tool in chemistry.