Atomic number

The atomic number which is also called the proton number is the number of protons in the nucleus in an atom.The atomic number identifies a chemical element.

In an atom of neutral charge the atomic number is equal to the number of electrons in an atom.  The atomic number is also closely related to the mass number which is the protons and neutons added in the nucleus of an atom.  The atomic number was originally intended to signify where an elements place is on the periodic table.  For example sodium is number 11 on the periodic table.  That means that it has 11 protons and 11 electrons.  Dmitri Mendeleev was the one who ordered the elements by atomic wheight

 click here to see definition of periodic table.  periodic table.

Atomic number is an important term because then in our studies of atoms we needed to know the number of protons, neutrons and electrons and an atom and the atomic number helps with this by identifying the number of protons in an atom.  The number of protons is also the same as the number of electrons.  The number of protons subtracted from the rounded atomic weight will give you the average number of neutrons.  That help you identify the structure of that atom also. 

 "Atomic number." wikpedia. 28 Mar 2008 <http://en.wikipedia.org/wiki/Atomic_number>.