Electrons and the Periodic Table

An atom is a system of one or more electrons bound to a nucleus. Here is a quantum microscope image of a hydrogen atom:

atom hydrogen quantum

Hydrogen has just one electron, which exists as a fuzzy probability cloud.

But it is easier to use a simple diagram:


In the center (marked "H" for "Hydrogen") is the nucleus with 1 proton, and around that is our one electron.

Electrons are attracted to protons, and are in their lowest energy state:

Play with it below ... discover patterns for yourself ... then learn more later.



The electrons don't always go where you expect. It is like packing things into a box, the items find their lowest energy locations, sometimes with subtle shifting going on.

It Causes Chemistry!

But the really cool thing is that the outermost electrons affect how each element bonds or reacts chemically with others.

hydrogen gas   H20 is water


And so it makes sense to group all elements that behave in a similar way into columns (called groups).

And the rows (called periods) show us how many shells.

There are also 4 main blocks that correspond roughly with the type of oribital (shown as the color of the block).

Have another play with the table and more for yourself.

(Note: the block starting at 57 etc belongs in the table next to number 56. And the block starting at 89 etc belongs in the table next to number 88.)