Why are atomic numbers important?

2 Answers
Mar 14, 2018

Well, it provides the basis of the Periodic Table, and it explicitly differentiates the different types of element based on an integral number.


Our modern conception of the elements uses #Z#, the atomic number, to represent the number of charged nuclear particles. And for #Z=1#, we gots hydrogen, #Z=2#, we gots helium,...#Z=92#, we gots uranium.

Now I don't know about you, but I think this classification is dam useful, and dam simple. And I think the symbol #Z# derives from the German word, #"Zahl"#, i.e. number, and from this developed the term #"Atomzahl"#, and hence the modern term #"atomic number"#.

Mar 14, 2018

The atomic number specifies the number of protons in an element. The atomic number also determines the number of electrons and dictates the behavior of an element.


The atomic number is the same as the number of protons in an atom or element. The protons have a positive charge so the atomic number gives the positive charge on the atom or element.

A neutral atom will have an equal number of negative electrons to balance the number of protons. So the atomic number also gives the number of electrons in a neutral atom.

The number of electrons determines the electron configuration of the atom. The electron configuration determines the behavior of the atom or element.

The atomic number tells us important information: The number of protons, the positive charge, the number of electrons the negative charge, and the typical behavior of the element based on the electron configuration.