Name____________________________
Date______
Period__
Electron Configuration Review:
Principle Energy
Level
Sublevels Present
Orbitals per
sublevel
Number of
electrons per
orbital
Total electrons in
the Energy Level
1
2
3
8
s
p
d
4
A. For the following please write the number of PEN present, the electron configuration
including boxes!
1. He-4
2. Na-23
3. Al-30
4. Ar-40
5. Ca-40
B. For the following fill in the electrons into the boxes according to the information
provided. Answer any accompanying questions. Remember each box represents an
orbital for one of the sublevels in the electron cloud.
P3
Li-7 E 3
1s22s1
N4
1s
2s
1. How many sublevels contain electrons?
2. Of these sublevels, how many are filled to their maximum capacity?
3. Which sublevels are filled completely?
4. Which sublevels are NOT filled completely?
5. What is the outermost (valence shell) energy level in an atom of Li?
6. How many valence electrons are present? Circle the sublevel(s) that contain
the valence electrons.
P7
N-14 E 7
N7
1s22s22p3
1s
2s
2p
7. How many sublevels contain electrons?
8. Of these, how many are completely filled? Name them.
9. Which sublevels are HALF filled?
10. How many orbitals are half-filled?
11. What is the valence shell of the electron cloud in N-14?
12. How many valence electrons are present? Circle the sublevel(s) that contain
them.
Finish the electron configuration and boxes. Remember Aufbau’s Principle:
P 19
K-39 E 19
1s22s22p63s23p6___
N 20
1s
2s
2p
3s
3p
13. How many completely filled sublevels are present?
14. How many completely filled orbitals are present?
15. How many orbitals are half filled?
16. How many energy levels contain electrons?
17. How many valence electrons are in K-39? Circle the sublevels that contain the
valence electron(s).
P
V-51 E
N
18. How many completely filled sublevels are present?
19. How many completely filled orbitals are present?
20. How many orbitals are half filled?
21. How many energy levels contain electrons?
22. How many valence electrons are in K-39? Circle the sublevels that contain the
valence electron(s).
Define the Octet Rule:
Define valence electron:
Bonding:
Chemical Bonding is an event that occurs between two atoms. In a chemical bond
the electrons from each atom are attracted to the nucleus the opposite atom, and as a
result a bond is formed.
Think of a chemical bond as a force of attraction between two atoms, that holds
them together. Chemical bonds form because of electrons. Specifically, it is the valence
electrons that are involved in chemical bonds.
Remember the octet rule: An atom is stable (happy) when it has 8 valence
electrons. An unstable atom (anything that has less than 8 valence) is considered
reactive. In other words, it will do what it takes to reach 8 valence!
One of the best ways to visualize why bonding occurs is to use the Lewis Dot
structures. If you recall Lewis Dot structures are represented with the symbol of the
element and surrounding the 4 sides of the symbol dots are placed to represent the
number of valence electrons present.
Please draw the Lewis Dot Structures for:
H
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
There are two major types of bonds that can form between atoms:
1. Ionic Bonds. In an ionic bond the valence electron(s) from one atom is/are
transferred to the second atom. Ionic bonds involve the formation of IONS. To
break it down even further, one atom gains and electron(s) and one atom loses an
electron(s).
Why? Remember, the atoms want to reach the magic number of 8 valence! By
giving up electrons or gaining them they reach their goal.
How? Follow the steps below.
Step 1. A sodium
atom begins with 1
valence – no where
near 8.
However, count how
many electrons are
in the second energy
level…
Step 2. Chlorine
starts with 7
valence. That’s
almost 8. If only it
can get one more it
would have 8
valence in the 3rd
energy level.
Step 3. If you guessed
correctly, the sodium
atom is eager to give up
its one valence electron
to chlorine. If it loses an
electron, sodium is now
a positively charged ion.
Why? Sodium would
then have a valence of 8
(in the second energy
level).
Also chlorine would then
complete its 3rd principle
energy level with 8 by
gaining this electron,
making it a negatively
charged ion. Both attain
the octet rule with a little
give and take.
Step 4. The transfer of electrons from one atom to another forms a
chemical bond between the two, “locking” them together as 1
compound. (Remember what a compound is?)
2. Covalent Bonds. In a covalent bond, electrons are not transferred from one atom
to another. Instead, electrons are shared between two atoms. Think of it as though
the two atoms are holding electron hands.
A. Each atom contributes an electron to an “electron pair”. This pair is shared
by both atoms and allows them to feel as though they have an extra electron.
In this way both atoms can reach a valence of 8.
Step 1. In each atom
of chlorine there are 7
valence. Both so close
to 8! Would either be
willing to give up a
valence? The answer
is no.
Step 2. So they
compromise. If
each share one
electron with
the other, then
each would feel
as though 8
valence were
present.
B. In some cases more than one pair of electrons can be shared between the
same two atoms. Multiple pairs can be formed between the same to atoms if it
helps them attain 8 valence. Using the hand-holding metaphor, the two atoms
are holding hands in a couple of places.
Each Oxygen atom
has 6 valence, close
to the octet rule.
Neither is willing to
lose electrons. If one
pair is shared then
both feel as those
there are 7 valence.
If a second pair
of electrons is
shared, then
both feel as
though the have
8 valence. Both
are now happy.
Not yet 8.
C. In some cases one atom may form covalent bonds with more than one other
element. In other words, some atoms will hold hands with multiple partners at
the same time.