Unit 5: Bonding
Overview- Honors Chemistry
Bonding
Satisfying octet rule;
Lowering energy and
increasing stability
Metallic
Ionic
(Bonding within and between
metals/alloys)
(Bonding between metals and
nonmetals)
Covalent
(Bonding between nonmetals)
Attraction between
ordered cations and
delocalized electrons
Transfer of electrons;
Electrostatic attraction
between ions with
opposite charges
Shared electrons
between positive
nuclei
Properties
Properties,
nomenclature, and
problem-solving
Properties,
nomenclature,
problem-solving, and
modeling
Enduring Understandings (Bonding #1)
I.
II.
Chemical bonds are attractive forces that connect atoms.
 Energy is always released (lowered) when bonds are formed.
 Energy is always required (put in) to break bonds.
The octet rule can be used to explain bonding between many atoms.
 Metals form an octet by losing valence electrons; delocalized electrons among metal cations (metallic bonding)
 Metals form cations and nonmetals form anions (both obtain octet); ions with opposite charges attract (ionic bonding)
III.
Properties can provide chemists with clues about the type of bonding present within a compound. No single property below is enough to
determine the type of bonding present. All available experimental evidence must be considered. Instrumental analysis is used to identify
unknown compounds in the laboratory.
 Metallic substances
Atoms and alloys- good conductors, malleability, ductility, luster, varying melting/boiling points
 Ionic substances
Formula units- lattice structure, brittle solids at room temp., high solubility in water (dissociation), good conductors in
solution
IV.
Chemists have developed systematic ways of naming chemical compounds (nomenclature).
 Ionic compounds
Group IA and IIA cations have the same name as their respective neutral metal.
d-block and p-block metals that form ions with multiple charges are named with Roman numerals
Monatomic anions are named by adding “-ide” ending to element name.
V.
REDOX reactions involve a transfer of electrons.
 OIL RIG
Oxidation involves loss of electrons
Reduction involves gain of electrons
Enduring Understandings (Bonding #2)
VI.
VII.
VIII.
IX.
X.
XI.
XII.
Bond character (type) is determined by calculating the electronegativity difference between bonding atoms.
 Nonpolar covalent
Zero electronegativity difference; equal sharing of electron density
 Polar covalent
Small to medium electronegativity differences; unequal sharing of electron density
 Ionic
Large electronegativity differences; transfer of electrons
The octet rule can be used to explain bonding between many atoms.
 Nonmetals share electron pairs (covalent bonding)
 Central atoms from the 2nd series generally abide by the octet rule, while larger atoms (3rd series and below) provide more room
for additional electron domains
Chemists use Lewis structures to model the bonding in simple covalent compounds.
 Localized treatment of electrons is “too good to be true” and often does not support experimentally determined bond lengths.
Valence Shell Electron Pair Repulsion (VSEPR) theory is used to predict the shape of molecules
 Electron domains are oriented as far apart as possible
 Lone pairs take up more space, because they are only bound by one nucleus
Properties can provide chemists with clues about the type of bonding present within a compound. No single property below is enough to
determine the type of bonding present. All available experimental evidence must be considered. Instrumental analysis is used to identify
unknown compounds in the laboratory.
 Covalent substances
Molecules- varying conductivity (many non-electrolytes), solubility (many insoluble in water), and melting/boiling points
(many liquid or gas at room temp.)
Chemists have developed systematic ways of naming chemical compounds (nomenclature).
 Covalent compounds
Prefixes are used as well as “-ide” ending.
Polar molecules contain a net dipole that results from the combination of one or more polar covalent bonds.
XIII.
“Like Dissolves Like” is a useful way to predict solubility
XIV.
Intermolecular forces are attractions between molecules due to permanent (dipole interactions) and instantaneous (dispersion forces)
dipoles
 The boiling points of substances containing intermolecular forces are much greater than similar substances lacking the attractive
forces.
 Hydrogen bonding is responsible for many of the unique properties of water.