SN ____
Name _____________________________
Period ____
Date __________________
Valence Electrons & Dot Diagrams
Valence Electrons
① What are valence electrons?
② How do I determine valence electrons from the periodic table?
a.
b.
c.
d.
e.
Locate the element on the periodic table.
Exclude groups 3-12 (These are transitional metals, which have special circumstances),
Valence electrons increase in number as you count groups left to right, along a period.
Each new period begins with one valence electron.
Ex: Elements in group 1 have one valence electron; elements in group 2 have two
valence electrons; elements in group 13 have three valence electrons; elements in group
14 have four valence electrons; and so forth up to group 18 with have eight valence
electrons, except for helium, which has only two.
Drawing Dot Diagrams
① What is a Dot Diagram?
② What do you use a Dot Diagram for?
③ What is the maximum number of valence electrons an element can have?
④ Steps in creating a Dot Diagram…
a. Determine the element symbol: _____________
b. How many valence electrons does this element have? _________________
c. Write the element symbol and draw an imaginary box around it, this represents the nucleus.
d. Electrons are represented by dots around the symbol
e. The first 2 go together on the top, and then you place one on each side
before pairing them up.
f. This represents four orbitals, each holding a max of 2 electrons.
g. Done! This is your completed Dot Diagram.
h. The Dot Diagram can also be drawn for ions, recognizing that a negative charge means that
extra electrons have been acquired and that a positive charge means that electrons have
been lost.
i. Lewis Dot Structures for ions are always enclosed in brackets with the charge indicated on
the outside.
Lewis Dot Diagram Practice
1. Use the periodic table to determine the valence number for the following.
Element
Valence Number
Element
H
Ne
Li
Br
Mg
N
S
Ca
B
I
F
K
Sr
Rb
Al
Be
Se
Te
O
Na
Valence Number
2. Complete the table.
Element
P
N
Li
O
F
# of Valence
Electrons
Lewis Dot Diagram of
Neutral Atom
Ionic
Charge
Lewis Dot Diagram of ion
Mg
H
He
K
Ion Practice Worksheet
3. Complete the following chart
Element
Na
Ca
B
Ne
Cl
S
Lewis Dot Diagram of neutral atom
# electrons
being
gained/lost
Charge
on the
ion
Lewis Dot Diagram of ion