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GENERAL CHEMISTRY
Principles and Modern Applications
PETRUCCI
HERRING
MADURA
Chemical
Compounds
PHILIP DUTTON
UNIVERSITY OF WINDSOR
DEPARTMENT OF CHEMISTRY AND
BIOCHEMISTRY
TENTH EDITION
BISSONNETTE
3
Chemical Compounds
CONTENTS
3-1
Types of Chemical
Compounds and Their
Formulas
3-2
The Mole Concept and
Chemical Compounds
3-3
Composition of Chemical
Compounds
3-4
Oxidation States: A Useful
Tool in Describing Chemical
Compounds
3-5
Naming Compounds:
Organic and Inorganic
Compounds
3-6
Names and Formulas of
Inorganic Compounds
3-1
Types of Chemical Compounds and Their Formulas
 The common feature of all compounds is that they are composed of two or more
elements
 Two fundamental kinds of chemical bonds hold together the atoms in a compound
 Covalent bond: which involve a sharing of electrons between atoms, give rise to
molecular compounds
 Ionic bond: which involve a transfer of electrons from one atom to another, give
rise to ionic compound
Molecular Compounds
 Made up of discrete units called molecules , which typically consist of a small
number of nonmetal atoms held together by covalent bonds.
 They are represented by chemical formula
 The relative number of atoms are indicated by subscripts
 CCl4 = Carbon tetrachloride
 Empirical Formula: is the simplest formula for a compound
 The subscripts in an empirical formula are reduced to their simplest whole-
number ratio.
 Acetic acid (C2H4O2) and Glucose (C6H12O6) have the same empirical
formula of CH2O
 Molecular formula: based on an actual molecule of a compound.
 Empirical and molecular formulas tell us the combining ratio of the atoms in the
compound, they show nothing about how the atoms are attached to each other
Structural formula: shows the order in which atoms are bonded together in a
molecule and by what types of bonds
 Acetic acid: structural formula tell us that three of four H atoms are bounded to one
of the C atoms, and the remaining H atom is bonded to an O atom. Both of O atoms
are bonded to one of the C atoms, and the two C atoms are bonded to each other.
 The covalent bonds in the structural formula are represented by lines or dashes (—)
 (=): double covalent bond
(CH3COOH)
Figure 3-1 Several representations of the compound acetic acid
 Organic compounds: made up principally of carbon (C) and hydrogen (H), with
oxygen (O) and or nitrogen (N) as important constituent
 Each C atoms forms four covalent bonds
Empirical and numerical
formulas do not convey any
information about the spatial
arrangement of the atoms
Structural formulas can
sometimes show this
Ball and stick model
represent three dimensional
structure of the molecule
Atoms are represented by
small molecules and the bonds
between atoms by stick
Such model help us to
visualize distance between the
nuclei of atoms and geometrical
shapes of the molecules
Figure 3-2
Visualizations of (a) butane, (b) methylpropane, and (c) testosterone
 Different color are used to distinguish the various types of atoms in ball and stick
and space filling model
 The colored spheres are of different sizes, which correspond to the size difference
between the various atoms in the periodic table
Figure 3-3
Color scheme for use in molecular models
Ionic Compounds
 Atoms of almost all elements can gain or lose electrons to form charged
species called ions.
 Compounds composed of (+) or (-) ions are known as ionic compounds
+
Metals tend to lose electrons to form positively
charged ions called cations
-
Non-metals tend to gain electrons to form
negatively charged ions called anions
 Formula unit: is the smallest electrical neutral
collection of ions
 The ratio of Cl- and Na+ ions in NaCl is 1:1
 Magnesium chloride (MgCl2)
 Magnesium atoms lose two electron to become
magnesium ions (Mg2+)
 To become electrically neutral formula unit, there
must be two Cl- ions, each with a charge of 1-, for
every Mg2+ion
Na+
ClFIGURE 3-4
Portion of an ionic crystal and a
formula unit of NaCl
3-2
The Mole Concept and Chemical Compounds
 Formula mass
the mass of a formula unit in atomic mass units (u)
 Molecular mass
Mass of a molecule in atomic mass unit (u)
 The terms formula mass and molecular mass have the same meaning,
although when referring to ionic compounds
 Exp:
 Molecular mass of H2O
2 (atomic mass of H) + (atomic mass of O)
2(1.00794 u ) + (15.9994 u) =18.0153 u
 Anionic compound magnesium nitrate Mg(NO3)2
Formula mass Mg(NO3)2
Atomic mass Mg + 2[atomic mass N + 3(atomic mass O)]
24.3050 u + 2[14.0067 u + 3(15.9994 u] = 148.3148 u
Mole of a Compound
 Mole of a compound: is an amount of compound containing Avagadro’
number (6.02214 x 1023) of formula units or molecules.
 Molar mass: mass of one mole of compound- one mole of molecules of
molecular compound and one mole of formula unit of an ionic compound
 Exp:
 1 mol H2O = 18.153 g H2O = 6.0221 x 1023 H2O molecules
KEEP IN MIND
 That although molecular mass and molar mass sound similar and are related,
they are not the same.
 Molecular mass is the weighted-average mass of one molecule expressed in
atomic mass units, u.
 Molar mass is the mass of Avogadro’s number of molecules expressed in
grams per mole, The two terms have the same numerical value but different
units.
Molecular mass of H2O =18.153 u
Molar mass of H2O =18.153 g H2O/ mol H2O
Mole of an Element
 The atoms of some elements are joined together to form molecules . Bulk
sample of these elements are composed of collections of molecules.
 The molecular formulas of some elements
H2 O2
N2
F2
Cl2
Br2
I2
P4
S8
 H: has an
atomic mass of 1.00794 u and
molecular mass of 2.01588 u
 Its molar mass : 1.00794 g H or
2.01588 g H2 / mol H2O
 There are 8 sulfur atoms in a
sulfur molecules
 There are 4 phosphorous atoms
per molecule
Figure 3-5
Molecular forms of elemental sulfur and phosphorus
3-3 Composition of Chemical Compounds
Halothane
C2HBrClF3
Mole ratio
nC/nhalothane
Mass ratio
mC/mhalothane
M(C2HBrClF3) = 2MC + MH + MBr + MCl + 3MF
= (2 x 12.01) + 1.01 + 79.90 + 35.45 + (3 x 19.00)
= 197.38 g/mol
Calculating Percent Composition from a Chemical Formula
x 100%
Establishing Formulas from Experimentally Determined
Percent Composition of Compounds
 A chemist isolates a chemical compound and has no idea what it is
 The percent composition of the compound yield data needed to determine
formula
 Exp: 2-deoxyribose (a sugar that is a basic constituent of DNA)
 44.77% C
7.52% H
47.71% O
5 Step approach:
1. Choose an arbitrary sample size (100g).
44.77% C
7.52% H
47.71% O
2. Convert masses to amounts in moles.
44.77 g C x 1 mol C/12.011 g C = 3.727 mol C
7.52 g H x 1 mol H/1.008 g H = 7.46 mol H
47.71 g O x 1 mol 0/15.999 g O = 2.928 mol O
3. Write a formula.
C 3.727 H 7.46 O 2.928
4. Convert formula to small whole numbers: dividing each by smallest one.
C3.727/ 2.928 H7.46/ 2.928 O2.928/ 2.928 = C1.25 H2.5O
5. Multiply all subscripts by a small whole number to make the subscripts integral
C1.25 H2.5O= C5 H10O4
Simplest possible formula or empirical formula. Actual formula may C15H30O12 so on
Compare formula mass with the true molecular weight of the compound
2-deoxyribose = 134 u and the formula of C5 H10O4 is 134.1 u is the molecular formula
Combustion Analysis
 In the combustion analysis, a weighted sample of a compound containing carbon
(C) hydrogen (H) and oxygen (O) is burned in a stream of oxygen gases
 The water vapor and carbon dioxide gas produced in the combustion are
absorbed by appropriate substance
 After combustion, all C atoms in the sample are found in CO2, all H atoms are in
the H2O, O atoms in the CO2 and H2O could have came partly from the sample
and partly from the O gas consumed in the combustion.
3-4 Oxidation States: A Useful Tool in Describing Chemical
Compounds
 Related to the number of electrons that an atom loses, gains or otherwise appear to use
in joining with other atoms in compounds
Reducing agents
Metals tend to lose
electrons.
Na
+
Na+ + e-
Non-metals tend to
gain electrons.
Cl + e-
NaCl
Cl-
Oxidizing agents
3-5 Naming Compounds:
Organic and Inorganic Compounds
 It is necessary to give the names for the compound in addition to the formulizing
 We will see cases in which different compound have the same formula
 It is essential to distinguish among compound by name
Lead (IV) oxide
PbO2
Lead (II) oxide
PbO
(red brown)
(yellow)
Figure 3-7
Two oxides of lead
 These two compounds contain the same elements (lead and oxygen) but in
different proportions
Organic compounds: formed by C and H or C and H together with O, Ni, and a
few other elements
Inorganic compounds: that do not fit this description
3-6 Names and Formulas of Inorganic Compounds
Binary Compounds of Metals and Nonmetals
 Formed between two element
 Binary ionic compound: If one of the element is metal and the other is a
nonmetal, the binary compound is usually made up of ions
 To name the binary compound of metal and non metal
Write the unmodified name of metal
Then write the name of nonmetal, modified to end in -ide
 Ionic compounds, made up (+) and (-) ions, must be electrically neutral
 The total charge of the ions in a formula unit must be zero
 This means one Na+ and one Cl- in NaCl, one Mg2+ and two I- in MgI2 and so on
 Two binary compound containing
the same elements but in different
proportions
 Cu2O and CuO
In Cu2O the oxidation state (OS)
of copper is +1 and CuO it is +2
 The name of Cu2O: cuprous oxide
 The name of CuO: cupric oxide
 Similar
 FeCl2: ferrous chloride
 FeCl3: ferric chloride
 Use –ous ending for lower OS
 Use –ic for higher OS
Binary Compounds of Two Non-Metals
 If the two elements in a binary compound are both nonmetals the compound is a
molecular compound
The method of naming these compound is similar just discussed.
 Usually write the positive OS element first.
 HCl: hydrogen chloride
 Some pairs of nonmetals form more than one compound, we need to distinguish
among them
 We indicate relative number of atoms through prefixes
mono
1
penta
5
di
2
hexa
6
tri
3
hepta
7
tetra
4
octa
8
Binary Acids
 Acid is a substance that ionize or breaks down in water to produce hydrogen
ions (H+) and anions
 Binary acid is two element compound of H and a nonmetal
 Exp: Hydrogen chloride is a pure binary molecular compound
Their aqueous solution are acid: HCl ionize into hydrogen ions (H+) and
chloride ions (Cl-) in water
NH3 in water is not acid. It shows no tendency to produce H+ under any
conditions
 Naming: use prefix -hydro followed by the name of the other nonmetal
modified with an –ic ending
 The symbol (aq) signifies aqueous solution.
H2S(aq) = hydrosulfuric acid
HI(aq) = hydroiodic acid
HCl(aq) = hydrochloric acid
HBr(aq) = hydrobromic acid
HF(aq) = hydrofluoric acid
Polyatomic Ions
 Two or more atoms are joined together by covalent bond
 These ions are common, especially among the nonmetal
 Their names ranging from hypo- (lowest OS) to per- (highest OS)
 The common ending are –ite and –ate
Increasing oxidation state of nonmetal
(hypo___ite)
(__ite)
(___ate)
Increasing number of oxygen atoms :
(per___ate)
Oxoacids
 If one of the nonmetal is oxygen, the acid is called an oxoacid.
Naming is similar with the oxoanion (which are types of polyatomic anions)
 The ending –ous is used instead of –ite
 The ending –ic is used instead of –ate
The compound salt: replacement of the hydrogen of oxoacid by a metal such
as sodium.
Acid are molecular compounds
Salt are ionic compounds
3-7 Names and Formulas of Organic Compounds
Organic compounds abound in nature
Fats, carbohydrates and proteins are foods.
Propane, gasoline, kerosene, oil are fuels.
Drugs and plastics are produced by chemical industries.
 Carbon atoms form chains and rings to which other atoms are attached and act
as the framework of molecules.
 All organic compounds contain C atoms; almost all contain H atoms; and many
common ones have O, N or S atoms
 Organic compounds are mostly molecular, a few are ionic
Hydrocarbons
 Compounds containing only C and H are called hydrocarbon
 The simplest one C and four H atoms: methane (CH4)
 Increase in C atom increase the H atom
 Alkanes: hydrocarbons containing only single bond : simples
one is methane
 The names of alkanes are composed of two parts
 A words stem and the ending (suffix) -ane
Figure 3-9
Visualizations of some hydrocarbons
Alkenes: hydrocarbon molecules with one or
more double bonds between C atoms: simples one
is ethene
 The names of alkanes are composed of two
parts
 A words stem and the ending (suffix) –ene
Benzene is a molecule with six C atoms
arranged in a hexagonal ring
Figure 3-9
Visualizations of some hydrocarbons
 Isomers: molecules that have the same
molecular formula but different arrangement of
atoms in space
Exp: butane and methyl propane have the
same molecular formula, C4H10, but different
structural formula.
Visualizations of (a) butane, (b) methylpropane
Functional Groups
 Are individual atoms or grouping of atoms
that are attached to the carbon chains or rings
of organic molecules and give the molecules
their characteristic properties.
The –OH group (called the hydroxyl group)
in alcohol is one of the many functional
groups found in organic compound.
 Ethanol, CH3CH2OH, in which one of
the H atoms of ethane is replaced by an –
OH group
The name of alkane (ethane), with the final e
replaced by the suffix ol (ethanol) or yl (ethyl
alcohol)
All alcohols at least contain one –OH group
Figure 3-10
Visualizations of some alcohols
 Another important functional group is
carboxyl group, -COOH, or –CO2H which
confers acidic properties on a molecule.
 Compound containing the carboxyl group
are called carboxylic acid.
 C atom in carboxyl group is bounded to
the two O atom in two way (Fig 3-11a)

A single bond of O atom that is
also attached to H atom

Double bond to a lone O atom
Methanoic acid, HCOOH (Fig 3.11b)
 Methan indicates one C atom and the
–oic acid indicates a carboxylic acid
 The simples carboxylic acid
containing two C atoms is etanoic acid
more commonly known as acetic acid.
Figure 3-11
The carboxyl group and visualizations of two
carboxylic acids