LOCATING MAIN GROUP ELEMENTS ON THE PERIODIC TABLE
Given the electron
configuration or noble gas configuration for an element, it is possible to
determine its location on the Periodic Table without actually looking at a
Periodic Table.
* To tell which period
this element is in...
~ find the highest occupied
energy level for this element
You can do this by...
~ finding the largest coefficient number
The largest coefficient number is the number of the period where the element is
located.
* To tell which
"block" this element is in... (like
"s" block, "p" block, "d" block, etc)
~ find the highest occupied sublevel for this element
You can do this by...
~ finding the last lowercase letter written
The last lowercase letter written in the configuration is the "block"
where the element is located.
* To tell which group this
element is in...
~ find the highest occupied energy level for this
element
You can do this by...
~ finding the largest coefficient number
Then...
~ add up the exponents of the largest coefficient number
This gives you the number of valence electrons in the element.
You will then know that 1 valence electron indicates that the element is in
Group 1, 2 valence electrons indicates that the element is in Group 2, 3
valence electrons indicates that the element is in Group 13, 4 valence
electrons indicates that the element is in Group 14, 5 valence electrons
indicates that the element is in Group 15, 6 valence electrons indicates that
the element is in Group 16, 7 valence electrons indicates that the element is
in Group 17, and 8 valence electrons indicates that the element is in Group 18.
Look at the following
example.
EXAMPLE:
[Ar] 4s2 3d10 4p5
It is possible to tell the
period, group, and "block" where this element is located.
* Period -- largest coefficient number is
4, so element is in Period 4
* Block-- last lowercase letter written is "p", so
element is in "p" block
* Group-- largest coefficient number is 4... 2 electrons in
4s, 5 electrons in 4p --> total of 7 valence
electrons,
so this element is in Group 17.