1. Periodic Table Shortcut Noble Gas Notation Lewis Dot Structures

2. No, there are a few shortcuts.
When we write electron configurations, do we need to always start at the beginning?
No, there are a few shortcuts.

3. The first shortcut involves the placements of element’s on the periodic table
Let us look at the electron configurations from yesterday’s homework and bell work from today and see how they fall on the periodic table.
You will need 4 color pencils for this.

4. The only exception is He
So, the periodic table is arranged with electron configurations in mind
The only exception is He

5. Rows & Columns The rows correspond to the principle quantum number (n)
The sets of columns correspond to l quantum numbers and the amount of electrons in that orbital

6. Principle Quantum Number
Symbolized by n
Indicates the main energy level occupied the electron (the ring away from the nucleus)
Values of n are positive integers (1,2,3,4)
As n increases, so does the distance from the nucleus as well as the electron’s energy.

7. Rows The rows correspond to the principle quantum number (n)
In other words, each time you drop a row on the periodic table, you go out an energy level.
Be careful with the d and f areas
The d area is n-1 and the f area is n-2
La and Ac are considered the first f area elements

8. Columns
The sets of columns correspond to l quantum numbers and the amount of electrons in that orbital
Example: 2p4

9. So, by looking at the periodic table, one can find an element’s electron configuration

10. Let’s try some examples: Remember it should be a number then a letter then a superscript
What is the last orbital of tin (Sn)?
What is the last orbital of Ruthenium (Ru)?
What is the last orbital of Holmium (Ho)?
What element ends with the electron configuration of:
5s1
6p4
5f3

11. The second shortcut
We need to find a group of elements that have completed or full orbitals.
That group is the noble gases.
The last column on the periodic table.
This group can be used to write an abbreviated version of an element’s electron configuration.

12. Let’s look at yesterday’s homework again

13. How to write Noble Gas Notation
Find the closest noble gas to the element in atomic number without going over.
Write that noble gas’s symbol in brackets.
Go back to the beginning of the row and work back to the elements writing down the orbital sections and counting the electrons as you go.

14. Examples Pb As (Atomic Number – 33)
What is the closest Noble gas without going over? Ar
So, [Ar] C
[He]2s22p2 Pb
[Xe]
4s2
3d10
4p3
6s2
4f14
5d10
6p2

15. Lewis Dot Formulas Shows the valence electrons of an atom
Valence electrons are the electrons in the outermost energy level
The only electrons that are in the outermost energy level are s and p.
Therefore, the most valence electrons an atom can have is 8 (2 from the s and 6 from the p).

16. Lewis Dot Formulas
So, Lewis Dot Formulas are the chemical symbol surrounded by dots.
There will be one dot per electron in the s and p orbital
Hund’s rule must be followed

17. What is the Lewis Dot Structure for the following?
Francium
Arsenic
Hydrogen
Krypton
Oxygen

18. Review Video