1. Determining Shells and Valence Electrons
2008
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2. Where are the electrons?
As you know, electrons are always moving. They spin very quickly around the nucleus of an atom. As the electrons spin, they can move in any direction, as long as they stay in their shell. Any direction you can imagine - upwards, downwards, or sidewards - electrons can do it.
The atomic shell or orbital is the distance from the nucleus that the electron spins. If you are an electron in the first shell you are always closer to the nucleus than the electrons in the second shell.

3. Orbital Basics
Let's cover some basics of atomic orbitals. 1. A shell is sometimes called an orbital or energy level. 2. Shells are areas that surround the center of an atom. 3. The center of the atom is called the nucleus. 4. Electrons live in something called shells. 5. Each of those shells has a name.

4. There are a couple of ways that atomic orbitals are named
There are a couple of ways that atomic orbitals are named. You may have heard of the SPDF system before. Chemists also use letters to name the orbitals around a nucleus. They use the letters "k,l,m,n,o,p, and q". The "k" shell is the one closest to the nucleus and "q" is the farthest away.

5. Not all shells hold the same number of electrons
Not all shells hold the same number of electrons. For the first eighteen elements, there are some easy rules. The k-shell only holds two electrons. The l-shell only holds eight electrons. The m-shell only holds eight electrons (for the first eighteen elements). The m-shell can actually hold up to 18 electrons as you move farther along the periodic table. The maximum number of electrons you will find in any shell is 32.

6. We've been telling you that electrons reside in specific shells or move in specific directions. We can't really tell you exactly where an electron is at any moment in time. We can only approximate, or guess, where an electron is located. According to something called quantum theory, an electron can be found anywhere around the nucleus. Using advanced math, scientists are able to approximate, or guess, that electrons are in general areas. These general areas are called the shells.

7. Periods Each row is called a “period”
The elements in each period have the same number of shells
1st Period = 1 Shell
2nd Period = 2 Shells
3rd Period = 3 Shells
4th Period = 4 Shells

8. Groups Group 8 = 8 electrons Group 1 = 1 electron
Except for He, it has 2 electrons
Group 2 = 2 electrons
Each column is called a “group”
3, 4, 5, 6, 7
Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.
The electrons in the outer shell are called “valence electrons”

9. Transition Metals
Transition Metals have slightly different rules for shells and valence electrons.
This is something you will learn about in High School Chemistry.

10. Determine the number of shells and the number of valence electrons for:
Carbon - C
2nd Period = 2 shells
4th Group =
4 valence
electrons

11. Determine the number of shells and the number of valence electrons for:
Sodium - Na
3rd Period = 3 shells
1st Group =
1 valence
electron

12. Write your answers on your handout.Ne
Name the element.
Number of shells ?
Valence electrons ?

13. Write your answers on your handout.Ne
Name the element.
Number of shells ?
Valence electrons ?
Neon
2nd Period = 2 shells
8th Group = 8 valence
electrons

14. Write your answers on your handout.
Name the element.
Number of shells ?
Valence electrons ?

15. Write your answers on your handout.
Name the element.
Number of shells ?
Valence electrons ?
Hydrogen
1st Period = 1 shell
1st Group = 1 valence
electron

16. Write your answers on your handout.Be
Name the element.
Number of shells ?
Valence electrons ?

17. Write your answers on your handout.Be
Name the element.
Number of shells ?
Valence electrons ?
Beryllium
2nd Period = 2 shells
2nd Group = 2 valence
electrons

18. Write your answers on your handout.
Name the element.
Number of shells ?
Valence electrons ?

19. Write your answers on your handout.
Name the element.
Number of shells ?
Valence electrons ?
Sulfur
3rd Period = 3 shells
6th Group = 6 valence
electrons

20. Write your answers on your handout.K
Name the element.
Number of shells ?
Valence electrons ?

21. Write your answers on your handout.K
Name the element.
Number of shells ?
Valence electrons ?
Potassium
4th Period = 4 shells
1st Group = 1 valence
electron

22. Write your answers on your handout.He
Name the element.
Number of shells ?
Valence electrons ?

23. Write your answers on your handout.He
Name the element.
Number of shells ?
Valence electrons ?
Helium
1st Period = 1 shell
8th Group = 2 valence
electrons
Helium is the exception in Group 8.
Since it has just one shell, that shell can only fit 2 electrons instead of 8.
It is in this group because all the elements have a full outer shell.

24. Be sure to have all your answers on the worksheet.
End of Study Guide
Be sure to have all your answers on the worksheet.