Name
Unit: Covalent Bonding and Nomenclature
Text Reference: pages 161-163
Date
Chemical Bonding (Predicting Bond Types)
What is a chemical
bond?
A chemical bond is a
atoms or ions in a chemical compound.
Why do elements form
chemical bonds?
Uncombined elements have relatively high
Atoms will
,
, or
electrons in order to chemically combine with other atoms.
By combining with other atoms, atoms
energy and create more
.
between
.
valence
potential
What two factors
determine whether or not
a chemical bond will
form?
The two factors that determine whether or not a chemical bond will form are:
1.
the
of the atoms involved
2.
the
the atoms have for electrons
How is the type of
chemical bond formed
between two atoms
determined?
The type of chemical bond formed depends upon the degree to which the
between the atoms.
valence electrons are
What happens in
covalent bonding?
In a covalent bond, valence electrons are
atoms.
How can covalent bonds
be classified?
Covalent bonds can be
What happens in ionic
bonding?
by the
or
.
In a nonpolar covalent bond, electrons are shared
Bonding which occurs between two atoms of the same element is an
example of nonpolar covalent bonding.
Examples:
.
In a polar covalent bond, electrons are shared
.
In an ionic bond, valence electrons are
between atoms.
One atom
(
form a
electrons to form a
) and the other atom
(
).
electrons to
Which category of
elements tends to gain
electrons?
tend to gain electrons and form anions.
Which category of
elements tends to lose
electrons?
tend to lose electrons and form cations.
What is
electronegativity?
The degree to which bonding between atoms of two elements is ionic or
covalent can be estimated by
in the
elements’ electronegativities (∆EN). The
the
the attraction the
electronegativity value, the
atom has for another atom’s electrons.
1
How can you determine
the type of bond that will
form?
The degree to which bonding between atoms of two elements is ionic or
covalent can be estimated by
in the
elements’ electronegativities (∆EN).
∆EN (Difference in Electronegativity)
≤0.2
0.2 to 1.7
≥1.7
Type of Bond
Nonpolar Covalent
Polar Covalent
Ionic
What type of bond would
form between an atom of
nitrogen and an atom of
chlorine?
Nitrogen has an electronegativity value of
.
Chlorine has an electronegativity value of
.
The difference in electronegativity values for nitrogen and chlorine is
∆EN =
Therefore the type of bond formed would be
. The
electrons would be shared
.
What type of bond would
form between an atom of
hydrogen and an atom of
chlorine?
Hydrogen has an electronegativity value of
.
Chlorine has an electronegativity value of
.
The difference in electronegativity values for nitrogen and chlorine is
∆EN =
Therefore the type of bond formed would be
. The
.
electrons would be shared
What is a dipole?
A bond formed between atoms which are
is
called a dipole.
a) In the bond formed between hydrogen and chlorine, the
would form the negative dipole (symbolized by δ-) because it has the
electronegativity value.
b) The
would form the positive dipole (symbolized by
+
δ ) because it has the
electronegativity value.
What type of bond would
form between an atom of
lithium and an atom of
chlorine?
.
Lithium has an electronegativity value of
Chlorine has an electronegativity value of
.
The difference in electronegativity values for nitrogen and chlorine is
∆EN =
Therefore the type of bond formed would be
. The
between atoms.
electrons would be
2
The
ion, also known as a
would lose electrons and form a
.
The
ion, also known as an
would gain electrons and form a
.
You Try It
1.
Complete the following table.
Electronegativity ∆EN
Compound Elements
K
KF
F
O
O2
O
I
ICl
Cl
Bond Type
2.
For each of the bonds in question 1 that were polar covalent,
identify the negative dipole (δ-) and the positive dipole (δ+).
3.
Elements that exist as two atoms chemically bonded together are
called diatomic elements. The diatomic elements are hydrogen,
bromine, oxygen, nitrogen, chlorine, iodine, and fluorine. (You need
to memorize the diatomic elements.) What type of chemical bond
exists between the diatomic elements?
4.
Using the three classifications of bonds discussed, predict the type
of bond that is most likely to be present in compounds made from
elements of groups 1 (1A) and 17 (7A).
5.
Using the three classifications of bonds discussed, predict the type
of bond that is most likely to be present in compounds made from
elements of groups 16 (6A) and 17 (7A).
6.
Arrange the following chemical bonds in order of least covalent to
most covalent: H-H, H-Cl, H-Br, Li-Cl
3