Chemistry Reference
In-Depth Information
Use the following Lewis Dot Notations to answer questions 5-8.
H
H
H
H
HC
H
C
H
C
H
C
H
H
HC
CH
A.
C.
HC
H
C
H
H
OS
O
B.
D.
5.
Which diagram shows a triple covalent bond?
6.
Which diagram shows a total of 13 single covalent bonds?
7.
Which diagram shows a double covalent bond?
8.
Which diagram shows a compound that has the ability to form a
coordinate covalent bond?
Lesson 4 - 4 : Structural Formulas
In our last lesson, we discussed the procedures for constructing Lewis
dot diagrams for compounds. Although these diagrams can be very useful,
especially for smaller molecules, they can become unwieldy when used for
larger molecules. It can be time-consuming to add the dots that represent
valence electrons, and the detail that these diagrams show for nonbonding
electrons is not always necessary. It is more common to use a structural
formula to graphically represent a molecule. A structural formula is a for-
mula that uses elemental symbols to represent atoms and dashed lines to
show covalent bonds. Structural formulas show the general shape of a
molecule, but the exact bond angles aren't represented.
If you have become comfortable with constructing Lewis dot diagrams
for molecules, then drawing most structural formulas should seem fairly
easy. For the most part, the structural formula for a molecule looks just
like its Lewis dot diagram, except that pairs of bonding electrons are re-
placed with dashed lines and nonbonding electrons are usually left out of
the diagram completely. Figure 4-4a on page 128 compares the Lewis dot
diagrams and structural formulas for several common compounds.
You can learn a great deal about structural formulas by comparing the
formulas in Figure 4-4a. Compare the Lewis dot diagram for water to the
structural formula for the same compound. Each single bond between the
oxygen atom and a hydrogen atom is represented by a pair of dots in the
Lewis diagram and by a dashed line in the structural formula. Notice also
