Chem 121
In-class Assignment #3
Names: _______________________________________________________________________
Part 1: Electron Configuration and Valence Electrons
1. Without looking in your book (except for the inside front cover), fill out the following table:
Name of
Element
Carbon
Symbol
Atomic
number
# electrons in
shell 1
# electrons in
shell 2
# electrons in
shell 3
2
6
0
2
2
0
2
8
8
14
F
H
Sodium
Sulfur
15
B
12
2. Finish filling out the table below with chemical symbols, using the above information.
Level containing
Valence electrons
1
2
3
1
2
# VALENCE ELECTRONS
3
4
5
6
7
8
He
N/A
N/A
N/A
Ne
Li
Al
N/A
N/A
N
N/A
Cl
3. Do you see a pattern in the above table? Explain. (Hint: look inside the front cover of your
book!)
4. Write the electron configuration, the abbreviated (noble gas) electron configuration and draw
the electron-dot symbol for:
(a) Ca
(b) O
Part 2: Ions and Ionic Compounds
1. Fill out the table for the following elements that form anions:
Name of
Element
Symbol
Phosphorous
Oxygen
Fluorine
Chlorine
P
O
F
Cl
# of valence
electrons
# of electrons needed
to GAIN to have an
octet
Symbol of
ion
2. Fill out the table for the following elements that form cations:
Name of
Element
Symbol
Calcium
Aluminum
Beryllium
Iron
Ca
Al
Be
Fe
# of valence
electrons
# of electrons needed
to LOSE to have an
octet
Symbol of
ion
3. Give the name AND the formula of the ionic compound that will form from the following
ions. Identify the anion and the cation.
(a) The ion formed when Mn loses 2 electrons, and the ion formed from iodine
(b) The ion formed from Ca and the ion formed from chlorine
(c) Nitrate, NO3-, and the ion formed when iron loses 2 electrons
4. Is it possible for Na and Al to form an ionic compound together? Why or why not?