DATE ___________________
NOTES-030
CHEM 110 (BEAMER)
xNOTES-30:x Valence Electrons-01
DETERMINING VALENCE ELECTRONS
I.
Valence Electrons
are the

Determining the

located on the
valence electrons is responsible for

II.
(Please take out your periodic tables, you will need them for the remainder of the class period.)
This method is
of an atom.
.
from
. When you get your periodic table for
Practice 1)
How many valence electrons does beryllium have?
Practice 2)
How many valence electrons does aluminum have?
Practice 3)
How many valence electrons does nitrogen have?
Practice 4)
How many valence electrons does chlorine have?
do the following:
Page 1 of 4
DATE ___________________
III.
NOTES-030
Determining the

from
This is the
A.
B.
.
to determine the number of
method
CHEM 110 (BEAMER)
, because the
with transition elements.
Steps
1.
Write the full electron configuration.
2.
Find the highest orbital number (the first number).
3.
Circle every orbital with the number ID’d in Step 2.
4.
Count the valence electrons, and add ‘em up.
5.
Draw the Lewis Structure.
Example: Determine the number of valence electrons of sulfur using its electron configuration.
1.
Write the full electron configuration.
2.
Find the highest orbital number (the first number).
3.
Circle every orbital with the number ID’d in Step 2.
4.
Count the valence electrons, and add ‘em up.
Page 2 of 4
DATE ___________________
C.
D.
NOTES-030
CHEM 110 (BEAMER)
Example: Determine the number of valence electrons of strontium using its electron configuration.
1.
Write the full electron configuration.
2.
Find the highest orbital number (the first number).
3.
Circle every orbital with the number ID’d in Step 2.
4.
Count the valence electrons, and add ‘em up.
Example: Determine the number of valence electrons of manganese using its electron configuration.
1.
Write the full electron configuration.
2.
Find the highest orbital number (the first number).
3.
Circle every orbital with the number ID’d in Step 2.
4.
Count the valence electrons, and add ‘em up.
Page 3 of 4
DATE ___________________
E.
F.
NOTES-030
CHEM 110 (BEAMER)
Example: Determine the number of valence electrons of antimony (Sb) using its electron configuration.
1.
Write the full electron configuration.
2.
Find the highest orbital number (the first number).
3.
Circle every orbital with the number ID’d in Step 2.
4.
Count the valence electrons, and add ‘em up.
At your desks: Determine the number of valence electrons from the electron configuration. Show your work.
Practice-1)
sodium
Practice-2)
bromine
Practice-3)
iridium (Ir)
Answer Key
Practice-1)
Na:
1s2 2s2 2p6
3s1
1
Practice-2)
Br:
1s2 2s2 2p6
3s2

1 valence electron
3p6 4s2 3d10 4p5
2
Practice-3)
Ir:
1s2 2s2 2p6
3s2
+
5

7 valence electrons
3p6 4s2 3d10 4p6 5s2 4p10 5p3 6s2 4f14 5d7
2

2 valence electrons
Page 4 of 4