1. Periodic Table Study Guide Determining Shells and Valence Electrons

2. 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

3. Groups Group 8 = 8 valence e- Group 1 = 1 valence e-
Except for He, it has 2 electrons
Group 2 = 2 valence e-
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”

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

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

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

7. Write your answers in your notebook.Ne
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Neon 10
10 p+; 10 n
10 e-
2 (period 2)
8 (group VIII)

8. Write your answers in your notebook.H
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Hydrogen 1
1p+; 0 n
1 e-
1 (period 1)
1 (group I)

9. Write your answers in your notebook.Be
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Beryllium 4
4p+; 5 n
4 e-
2 (period 2)
2 (group II)

10. Write your answers in your notebook.
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Sulfur 16
16p+; 16 n
16 e-
3 (period 3)
6 (group VI)

11. Write your answers in your notebook.
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Potassium 19
19 p+; 20 n
10 e-
4 (period 4)
1 (group I)

12. Write your answers in your notebook.He
Name the element:
Atomic number:
Number of p+ and n in nucleus:
Number of e- in electron cloud:
Number of e- energy shells:
Valence electrons:
Helium 2
2 p+; 2n
2 e-
1 (period 1)
2 (group VIII)

13. Remember This About He:
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.