Question

How are elements arranged on the Periodic Table?

Answer 1

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?