How are elements arranged on the Periodic Table?

1 Answer
May 9, 2017

Answer:

By reference to their electronic structure...............

Explanation:

The Periodic Table DIRECTLY reflects the electronic structure of a given element. Elements are placed in columns, i.e. #"Groups"#, which reflects the number of valence electrons, and then placed in rows, in #"Periods"#, which is a measure of the distance of the #"valence electrons"# (i.e the outermost electrons) from the nuclear core. As a bonus, the #"Periodic Table"# also gives the average atomic mass of the each individual element. As always, an element is characterized by #Z#, #"the atomic number"#, the number of positively charged particles in the element's nucleus. #Z# also gives the number of electrons in the neutral element. Why should this be so?