Chemistry Reference
In-Depth Information
Which orbital notation matches up to each of the following elements?
3.
Chlorine
5.
Fluorine
7.
Magnesium
4.
Helium
6.
Lithium
8.
Boron
Lesson 3 - 6 : Lewis Dot Notation
Another type of notation that is used in chemistry is called Lewis dot
notation. In Lewis dot notation, the kernel of the atom—that is, the nucleus
and all of the inner electrons—is represented by the elemental symbol.
The valence electrons are represented by dots, and each of the four sides
around the elemental symbol represents one of the orbitals in the valence
shell. The rules for orbitals still apply, so no side can have more than two
dots, and each of the “p” orbital sides gets one dot, before you double up.
Figure 3-6a shows the general configuration for the Lewis dot notation.
You can really place
the “s” orbital on any
side of the elemental
symbol, but in this
topic, I will usually be-
gin with the “s” orbital
on the left-hand side.
Let's start off with an
easy example.
Lewis Dot Notation
s orbital
p orbitals
p1
p3
s
p2
elemental symbol
Figure 3-6a
Example 1
Show the correct Lewis dot notation for the element beryllium.
The key to solving this type of problem is to look at the electron con-
figuration of the element. Beryllium, with an atomic number of 4, has 4
electrons, giving it an electron configuration of 1s
2
2s
2
. The nucleus and the
two electrons in the first energy level (1s
2
) make up the kernel of the atom,
and they are represented by the elemental symbol in our Lewis dot nota-
tion. The two electrons in the second energy level (2s
2
) represent the va-
lence electrons, which are represented by dots in the Lewis dot notation.
So, to construct the proper notation, we write the elemental symbol and
two dots to the left of the symbol, as shown here.
Be
