Chemistry Reference
In-Depth Information
(e)
The covalent bond in
is a chemical bond, not the intermolecular force
Table 13.5
Forces of
called hydrogen bonding.
Attraction
Practice Problem 13.14
Which of the following substances are
Chemical bonds
Covalent
Ionic
Metallic
Intermolecular forces
van der Waals forces
Dipolar attractions
Hydrogen bonding
expected to form hydrogen bonds?
(a)
H
2
O
(b)
CH
3
OH
(c) NH
3
All the forces of attraction discussed so far are outlined in Table 13.5.
Snapshot Review
❒
Intermolecular forces must be distinguished from chemical bonds.
Intermolecular forces are the forces
between
molecules; chemical
bonds are the bonds
within
molecules (and polyatomic ions) and
between ions.
ChemSkill Builder 14.4
A. Classify each of the following as an intermolecular force or a chemical
bond: (a) bond in
H
2
and (b) hydrogen bond.
Key Terms
Key terms are defined in the Glossary.
angular molecule (13.4)
atomic size (13.1)
bent molecule (13.4)
central atom (13.4)
controlled experiment (13.1)
dipole (13.5)
dipole moment (13.5)
electron affinity (13.2)
electronegativity (13.3)
electron group (13.4)
hydrogen bonding (13.6)
intermolecular force (13.6)
ionic size (13.1)
ionization energy (13.2)
linear molecule (13.4)
molecular shape (13.4)
nonlinear molecule (13.4)
nonpolar bond (13.3)
nonpolar molecule (13.5)
polar bond (13.3)
polar molecule (13.5)
second ionization energy (13.2)
sublimation (13.6)
tetrahedral molecule (13.4)
third ionization energy (13.2)
trigonal planar molecule (13.4)
trigonal pyramidal molecule (13.4)
van der Waals force (13.6)
Symbols/Abbreviations
(delta) (13.3)
Summary
T
he properties of atoms and molecules affect the prop-
erties of the substances they constitute. Ionic size is an
important property, affecting the ability of the atom to
gain or lose an electron. The size of an atom or ion in-
creases as electrons are added, decreases with greater
numbers of protons, and varies periodically if both elec-
trons and protons are varied (Section 13.1).
The ionization energy of an atom is the energy
required to remove an electron from it; the electron
affinity is the energy liberated when an electron is added
to the atom. Both of these quantities refer to gaseous
atoms producing gaseous ions. For some atoms, the
electron affinity is negative—that is, energy is required to
add an electron to the atom (Section 13.2).
Electronegativity is a semiquantitative measure of the
electron-attracting power of a bonded atom. The greater
the electronegativity, the more the atom attracts electrons.
Covalent bonding between atoms of different electroneg-
ativity yields polar bonds; that between atoms of the same
electronegativity yields nonpolar bonds (Section 13.3).
