Name:______________________________________________________________________________
Electron Configuration Discovery (Unit 3.7 and 3.8)
Introduction: This discovery is intended to help you see how the periodic table of the elements is organized, and to help
you learn about electron configurations. You will be given periodic table of the elements with abbreviated electron
configurations written in beneath the element symbols. Color the periodic table according to the instructions that
follow.
1.
The periodic table is divided up into columns called groups and rows called periods. How many of each are
there? _______ groups _______ periods
2. Find boron on the periodic table. Draw a heavy line down the left side of its box, then another line between B and
Al, another line between Al and Si, another line between Si and Ge, and so forth, making a zig-zag line all the way
down to between Po and At.
3. Elements to the left of the lines—but not touching them—are metals. Elements to the right of the lines (but again
not touching them) are nonmetals. Elements touching any of those lines share properties of both metals and
nonmetals and are called metalloids. Label your periodic table with “metals,” “nonmetals,” and “metalloids.”
Name one example of each, listing its element symbol.
metal: _______
nonmetal: _______ metalloid: _______
4. Some groups have special names. Use your textbook to find and label the Alkali Metals, Alkaline Earth Metals,
Halogens, and Noble Gases on your periodic table. Name one example of each, listing its element symbol.
Alkali Metal
Alkaline Earth Metal
Halogen
Noble Gas
5. Look at the electron configurations for elements 81 through 86. What four letters of the alphabet are used to
write electron configurations? (For now, don’t include the element symbols in brackets such as [Xe]. We’ll come
back to their meaning later.) These four letters represent different types of atomic orbitals (electron clouds) in
which electrons can reside.
Four letters:
_____,
_____,
_____,
and
_____
6. Find the block of elements that have electron configurations that end with an “s” along with a superscripted
number afterwards. For now, don’t worry about including helium. These elements form the s block.
 With a red colored pencil, marker, or crayon, draw lines to outline the s block.
How many columns wide is the s block? ____
 Notice the superscripted number on the letter “s.” What is the highest number you see?
 How does the number of columns wide relate to the highest superscripted number that you see?
Name:______________________________________________________________________________
7. Repeat the steps of question #4 to find and label the p, d, and f blocks, using the colors listed below to outline
each block. Complete the table below.
orbital
block
s block
p block
d block
f block
color of
block
red
yellow
green
blue
# of
columns wide
highest
superscript
8. The highest superscript tells you the maximum number of electrons that are found in a particular atomic orbital.
Do the p, d, and f blocks follow the same pattern as the s block?
9. Examine the electron configurations for all the elements in Group 1A on the periodic table. Look closely at the
last orbital (s, p, d, f) that is filled and the number (superscript) of electrons in that orbital. Examine other groups
on the periodic table. What pattern do you notice?
10. Complete the following table.
element
Be
He
period
electron configuration
1s22s2
1
3
[Ne]3s2
11. Look at the highest occupied energy level, which is shown as the highest of the large coefficient numbers. How
does the highest energy level compare with the period in which that element is found?
12. Complete the following table.
element
period
last coefficient
block letter
Na
K
Si
As
Sc
Mo
Ce
U
13. Look at the last occupied energy level, or the last coefficient in the table above. How does the last coefficient
compare to the period number for the S and P blocks? How does the last coefficient compare to the period
number for the D block? What about the F block?
Name:______________________________________________________________________________
14. The first part of an electron configuration can be abbreviated by enclosing in brackets the last noble gas that you
went past to represent the full electron configuration leading up to that element. For instance, you can write [Ne]
to represent 1s22s22p6, which can be a real timesaver. Decode these elements by finding out their element
symbol, and write their full electron configurations below.
symbol
short-hand electron configuration
[He]2s1
[Ne]3s23p4
[Kr]5s24d4
full electron configuration
15. Complete the following table. In the final column, calculate the sum of the superscripts for the full electron
configuration.
symbol
Be
Cl
Na
P
atomic #
# of electrons
sum of superscripts
16. How do the atomic number, the number of electrons, and the sum of the superscripts relate to each other?
17. You may have noticed that the electron configurations are missing for a few of the elements. Use clues from the
electron configurations of the neighboring elements to write the full electron configurations below.
symbol
electron configuration
O
Sm
18. Use your textbook to complete the Electron Dot Structure for each element.
Element
Electron Configuration
Valence
Lewis Dot Structure
Electrons
1s2 2s2 2p6
8
Ne
1s2 2s2 2p6 3s2 3p6
8
1s2 2s2 2p5
7
Na
1s2 2s2 2p6 3s1
1
As
1s2 2s2 2p6 3s2 3p64s23d104p3
Ar
F
Y
Cu
1s2 2s2 2p6 3s2 3p64s23d104p65s24d1
1s2 2s2 2p6 3s2 3p64s23d9
19. What are valence electrons? How can we calculate valance electrons from electronconfigurations?