MOLECULES, COMPOUNDS,

AND CHEMICAL EQUATIONS

Chapter 3

3.2 CHEMICAL BONDS

Compounds are composed of atoms held

together by chemical bonds.

Chemical bonds result from the attractions

between the charged particles (the electrons

and protons) that compose atoms.

Chemical bonds are classified into two types:

Ionic

Covalent

IONIC BONDS

Ionic bonds—which occur between metals

and nonmetals—involve the transfer of

electrons from one atom to another.

When a metal interacts with a nonmetal, it

can transfer one or more of its electrons to

the nonmetal.

The metal atom then becomes a cation.

The nonmetal atom becomes an anion.

IONIC BONDS

These oppositely charged ions attract one

another by electrostatic forces and form an

ionic bond.

The result is an ionic compound, which in

the solid phase is composed of a lattice—a

regular three-dimensional array—of

alternating cations and anions.

IONIC BONDS

COVALENT BONDS

Covalent bonds—which occur between two or

more nonmetals—involve the sharing of

electrons between two atoms.

When a nonmetal bonds with another nonmetal,

neither atom transfers its electron to the other.

Instead the bonding atoms share some of their

electrons.

The covalently bound atoms compose a

molecule.

Hence, we call covalently bonded compounds

molecular compounds.

3.3 REPRESENTING COMPOUNDS:

CHEMICAL FORMULAS

A compound is represented with its chemical

formula.

Chemical formula indicates the elements

present in the compound and the relative

number of atoms or ions of each.

Water is represented as H2O.

Carbon dioxide is represented as CO2.

Sodium Chloride is represented as NaCl.

Carbon tetrachloride is represented as CCl4.

Problem 23 on page 130

TYPES OF CHEMICAL FORMULAS

Chemical formulas can generally be

categorized into three different types:

Empirical formula

Molecular formula

Structural formula

TYPES OF CHEMICAL FORMULAS

An empirical formula gives the relative

number of atoms of each element in a

compound. (Lowest whole # ratio)

A molecular formula gives the actual number

of atoms of each element in a molecule of a

compound.

(a) For C4H8, the greatest common factor is 4.

The empirical formula is therefore CH2.

(b) For B2H6, the greatest common factor is 2.

The empirical formula is therefore BH3.

(c) For CCl4, the only common factor is 1, so the

empirical formula and the molecular formula

are identical.

TYPES OF CHEMICAL FORMULAS

A structural formula uses lines to represent

covalent bonds and shows how atoms in a

molecule are connected or bonded to each

other. The structural formula for H2O2 is

shown below:

Learn more about in chapter 10!!!

A molecular model is a more

accurate and complete way to

specify a compound.

A ball-and-stick molecular model

represents atoms as balls and

chemical bonds as sticks; how

the two connect reflects a

molecule’s shape.

The balls are typically color-

coded to specific elements.

Problem 25 on page 130

MOLECULAR MODELS

MOLECULAR MODELS

In a space-filling molecular model, atoms fill the space between each other to more closely represent our best estimates for how a molecule might appear if scaled to visible size.

3.4 AN ATOMIC-LEVEL VIEW OF ELEMENTS

AND COMPOUNDS

Elements may be either atomic or molecular.

Compounds may be either molecular or ionic.

VIEW OF ELEMENTS AND COMPOUNDS

Atomic elements exist in nature with single

atoms as their basic units. Most elements fall

into this category.

Examples are Na, Ne, C, K, Mg, etc.

Molecular elements do not normally exist in

nature with single atoms as their basic units;

instead, they exist as molecules—two or more

atoms of the element bonded together.

There only seven diatomic elements and they are H2, N2,

O2, F2, Cl2, Br2, and I2. (HOFBrINCl)

Also, P4 and S8 are polyatomic elements.

MOLECULAR ELEMENTS

MOLECULAR COMPOUNDS

Molecular compounds are usually composed

of two or more covalently bonded nonmetals.

The basic units of molecular compounds are

molecules composed of the constituent

atoms.

Water is composed of H2O molecules.

Dry ice is composed of CO2 molecules.

Propane (often used as a fuel for grills) is composed

of C3H8 molecules.

IONIC COMPOUNDS

Ionic compounds are composed of cations

(usually a metal) and anions (usually one

or more nonmetals) bound together by

ionic bonds.

The basic unit of an ionic compound is the

formula unit, the smallest, electrically neutral

collection of ions.

The ionic compound table salt, with the formula

unit NaCl, is composed of Na+ and Cl– ions in a

one-to-one ratio.

MOLECULAR AND IONIC COMPOUNDS

QUESTIONS

Do problems 27, 29, 31 on page 130

3.5 IONIC COMPOUNDS: FORMULAS AND

NAMES Summarizing Ionic Compound Formulas:

Ionic compounds always contain positive and

negative ions.

In a chemical formula, the sum of the charges of

the positive ions (cations) must equal the sum of

the charges of the negative ions (anions).

+ = -

The formula of an ionic compound reflects the

smallest whole-number ratio of ions.

IONIC COMPOUNDS: FORMULAS AND

NAMES The charges of the representative elements

can be predicted from their group numbers.

The representative elements forms only one

type of charge.

Transition metals tend to form multiple types

of charges.

Hence, their charge cannot be predicted as in

the case of most representative elements.

Ionic compounds can

be categorized into two

types, depending on

the metal in the

compound.

The first type contains

a metal whose charge

is the same from one

compound to another.

Whenever the metal in

this first type of

compound forms an

ion, the ion always has

the same charge.

NAMING IONIC COMPOUNDS

NAMING TYPE I IONIC COMPOUNDS

NAMING BINARY IONIC COMPOUNDS OF

TYPE I CATIONS

Binary compounds contain only two different

elements. The names of binary ionic

compounds take the following form:

NAMING TYPE I BINARY IONIC COMPOUNDS

For example, the name for KCl consists of the

name of the cation, potassium, followed by

the base name of the anion, chlor, with the

ending -ide.

KCl is potassium chloride.

The name for CaO consists of the name of the

cation, calcium, followed by the base name of

the anion, ox, with the ending -ide.

CaO is calcium oxide.

BASE NAMES OF MONOATOMIC ANIONS

The base names of some nonmetals, and their most common charges in ionic compounds, are shown in Table 3.3.

Do problems 33 and 37

NAMING TYPE II IONIC COMPOUNDS

The second type of ionic compound contains

a metal with a charge that can differ in

different compounds.

The metals in this second type of ionic

compound can form more than one kind of

cation (depending on the compound).

Its charge must therefore be specified for a

given compound.

TYPE II IONIC COMPOUNDS

Iron, for instance, forms a 2+ cation in some

of its compounds and a 3+ cation in others.

Metals of this type are often transition

metals.

FeS Here iron is +2 cation (Fe2+).

Fe2S3 Here iron is +3 cation (Fe3+).

Cu2O Here copper is +1 cation (Cu+).

CuO Here copper is +2 cation (Cu2+).

Some main group metals, such as Pb, Tl, and Sn,

form more than one type of cation.

TYPE II IONIC COMPOUNDS

NAMING TYPE II BINARY IONIC

COMPOUNDS

For these types of metals, the name of the

cation is followed by a roman numeral (in

parentheses) that indicates the charge of

the metal in that particular compound.

For example, we distinguish between Fe2+ and

Fe3+ as follows:

Fe2+ Iron(II)

Fe3+ Iron(III)

NAMING TYPE II BINARY IONIC

COMPOUNDS The full names for compounds containing

metals that form more than one kind of

cation have the following form:

The charge of the metal cation can be determined by

inference from the sum of the charges of the nonmetal.

NAMING TYPE II BINARY IONIC

COMPOUNDS For example, to name CrBr3 determine the

charge on the chromium.

Total charge on cation + total anion charge = 0.

Cr charge + 3(Br– charge) = 0.

Since each Br has a –1 charge, then

Cr charge + 3(–1) = 0

Cr charge –3 = 0

Cr = +3

Hence, the cation Cr3+ is called chromium(III), while

Br– is called bromide.

Therefore, CrBr3 is chromium(III) bromide.

TYPE II CATION

Do problems 34, 38, 39, and 40 on page 131

POLYATOMIC ION

Many common ionic compounds contain

ions that are themselves composed of a

group of covalently bonded atoms with an

overall charge.

This group of charged species is called

polyatomic ions.

NaNO3 contains Na+ and NO3–.

CaCO3 contains Ca2+ and CO32–.

KClO Contains K+ and ClO–.

NAMING IONIC COMPOUNDS CONTAINING

POLYATOMIC IONS

We name ionic compounds that contain a

polyatomic ion in the same way as other ionic

compounds, except that we use the name of

the polyatomic ion whenever it occurs.

For example, NaNO2 is named according to

its cation, Na+, sodium, and

its polyatomic anion, NO2–, nitrite.

Hence, NaNO2 is sodium nitrite.

COMMON POLYATOMIC IONS

OXYANIONS

Most polyatomic ions are oxyanions, anions

containing oxygen and another element.

Notice that when a series of oxyanions contains

different numbers of oxygen atoms, they are

named according to the number of oxygen

atoms in the ion.

If there are two ions in the series, the one with more oxygen atoms has the ending -ate, and

the one with fewer has the ending -ite.

For example, NO3

– is nitrate SO42– is sulfate

NO2– is nitrite SO3

2– is sulfite

OXYANIONS

If there are more than two ions in the series

then the prefixes hypo-, meaning less than,

and per-, meaning more than, are used.

ClO– hypochlorite BrO– hypobromite

ClO2– chlorite BrO2

– bromite

ClO3– chlorate BrO3

– bromate

ClO4– perchlorate BrO4

– perbromate

Problems 35, 36, 41-44 on page 131

AGENDA FOR WEDNESDAY

Check problems 35, 36, 41-44

Return polyatomic ion quizzes

Return test and discuss test corrections

More review on ionic compounds

Hydrated compounds

Check answers on worksheet.

Questions

Quick Review

Hydrated compounds

Molecular Compounds

Naming Acids

Write the names for the following compounds:

NaBr SrS

Mg3P2 Ti(SO4)2

FePO4 K3N

NH4I CoCO3

ZnI2 Mn(NO3)3

CuOH Zn(NO2)2

Write the formulas for the following chemical

compounds:

nickel (III) sulfide

manganese (II) phosphate

silver acetate

potassium carbonate

ammonium oxide

tin (IV) selenide

lead (IV) sulfite

copper (II) bicarbonate

sodium phosphide

QUICK REVIEW

Write the names for the following compounds:

Mg3P2 FePO4

Mn(NO3)3 NH4I CuOH Zn(NO2)2

Write the formulas for the following chemical compounds:

nickel (III) sulfide

manganese (II) phosphate

silver acetate

potassium carbonate

HYDRATED IONIC COMPOUNDS

Hydrates are ionic compounds containing a

specific number of water molecules

associated with each formula unit.

For example, the formula for epsom salts is

MgSO4 • 7H2O.

Its systematic name is magnesium sulfate

heptahydrate.

CoCl2 • 6H2O is cobalt(II)chloride hexahydrate.

Common hydrate prefixes

hemi = ½

mono = 1

di = 2

tri = 3

tetra = 4

penta = 5

hexa = 6

hepta = 7

octa = 8

Other common hydrated

ionic compounds and their

names are as follows:

CaSO4 • 1/2H2O is called calcium

sulfate hemihydrate.

BaCl2 • 6H2O is called barium

chloride hexahydrate.

CuSO4 • 6H2O is called copper

sulfate hexahydrate.

Do Problems 45 and 46 on page

131.

HYDRATES

BINARY MOLECULAR COMPOUNDS

(COVALENT COMPOUNDS)

No ions form

Elements share electrons

ALWAYS between two nonmetals

Use prefixes to indicate the # of atoms

present

MOLECULAR (COVALENT) COMPOUNDS

mono = 1 hexa = 6

di = 2 hepta = 7

tri = 3 octa = 8

tetra = 4 nona = 9

penta = 5 deca = 10

NAMING COVALENT COMPOUNDS

Prefixes are always used to indicate the number

of atoms

Only time a prefix is not used mono- for the first

element.

So, if only one of the first element then no prefix is

used

If the numerical prefix ends with the letter a or o

and the name of the element begins with an a or

o the last letter of the prefix is dropped.

WRITING FORMULAS FROM NAMES

Use prefixes to tell you how many of each atom

you need in the formula.

DO NOT SIMPLIFY!!!!

Do problems 47-50 on page 131.

Do Molecular Compound side of worksheet

from yesterday.

ACIDS

Acids are molecular compounds that release

hydrogen ions (H+) when dissolved in water.

Acids are composed of hydrogen, usually

written first in their formula, and one or more

nonmetals, written second.

HCl is a molecular compound that, when

dissolved in water, forms H+(aq) and Cl–(aq) ions,

where aqueous (aq) means dissolved in water.

ACIDS

Acids are molecular compounds that form H+

when dissolved in water.

To indicate the compound is dissolved in water (aq) is

written after the formula.

A compound is not considered an acid if it does not

dissolve in water.

Sour taste

Dissolve many metals

such as Zn, Fe, Mg; but not Au, Ag, Pt

Formula generally starts with H

e.g., HCl, H2SO4

Binary acids have H+1 cation and nonmetal anion.

Oxyacids have H+ cation and polyatomic anion.

ACIDS

NAMING BINARY ACIDS

Write a hydro- prefix.

Follow with the nonmetal name.

Change ending on nonmetal name to –ic.

Write the word acid at the end of the name.

REVIEW

Silicon Dioxide Copper (II) Bicarbonate

Sodium Phosphide Arsenic Pentachloride

Selenium Tetrafluoride Lead (IV) Sulfite

PCl3` Cl2O7

Al2O3 Ba3P2

Fe(OH)3 Mg(NO2)2

SF6 N2O3

ACIDS

Anion doesn’t contain oxygen

Prefix hydro-

Name anion

Suffix –ic

Add acid

HCl (aq)

H2S (aq)

HBr (aq)

HF (aq)

Notice the formulas have a zero charge. Like ionic compounds

NAMING OXYACIDS

If polyatomic ion name ends in –ate, then

change ending to –ic suffix.

If polyatomic ion name ends in –ite, then

change ending to –ous suffix.

Write word acid at the end of all names.

oxyanions ending with -ate

oxyanions ending with -ite

ACIDS

Anion contains oxygen-Polyatomic Ions

Name formed from the root name of the anion with a

suffix –ic or –ous

Anion ends in –ate change to –ic

I ate something icky.

Anion ends in –ite change to –ous

I took a bite of something delicious.

H3PO4 (aq)

H2SO4 (aq)

H2SO3 (aq)

HNO3 (aq)

HNO2 (aq)

Stem changes to:

Sulfide Hydrosulfuric acid

Sulfate Sulfur Sulfuric acid

Sulfite Sulfurous acid

Phosphate Phosphor Phosphoric acid

Phosphite Phosphorous acid

Anion Ending Acid Name

-ide hydro-(stem)-ic acid

-ate (stem)-ic acid

-ite (stem)-ous acid

ACID NOMENCLATURE REVIEW

No Oxygen

w/Oxygen

1. H2S (aq)

2. HClO3 (aq)

3. HC2H3O2 (aq)

NAME THE FOLLOWING

hydrosulfuric acid

chloric acid

acetic acid

1. H2S (aq)

2. HClO3 (aq)

3. HC2H3O2 (aq)

Name the Following

WRITING FORMULAS FOR ACIDS

When name ends in acid, formulas starts with H.

Write formulas as if ionic, even though it is

technically molecular. (H is a nonmetal that forms

an ion in solution)

Hydro- prefix means it is binary acid; no prefix

means it is an oxyacid.

For oxyacid

if ending is –ic, polyatomic ion ends in –ate.

if ending is –ous, polyatomic ion ends in –ite.

Make sure to include the (aq) after the formula.

BASES

Same as ionic most of your bases have hydroxide

as their anion.

Ca(OH)2

NaOH

Do problems 51-54.

Do problems 55-58.

Assignments

Test corrections due on Monday!

Types of compounds WS (front and back) due

Tuesday.

Extra credit WS due on Tuesday.

Read and take notes on pages 107-116 for

Monday.

Naming Acid Ws due before you can got to lunch.

Turn in test corrections, make sure to staple your

original tests to your corrections.

Get out naming acids nomenclature WS-just going

to check answers

Reminders

Types of compounds WS (front and back) due

tomorrow.

Extra credit WS due tomorrow.

MOLAR MASS

Molar Mass-the mass in grams of one mole of

the compound (molecular weight)

Obtained by summing the masses of the

component atoms in the compound.

CH4-breaks down into

1 mol C= 12.01 grams

4 mol H = 4 x 1.008 grams =4.032 grams

1 mol CH4 = 16.04 grams

1 mol of element = grams (mass on the periodic

table)

1 mol of a compound = 6.022 x 1023 molecules of

that compound

1 mol of an element = 6.022 x 1023 atoms

1 mol of a compound = molar mass

Compounds are made of elements

Molecules Atoms

Molecules are made up of atoms

PROBLEMS PAGE 132

59 c & d

61 c & d

62 c & d

63 c & d

65 c & d

67 b & c

Turn in Naming WS

Turn in Extra Credit

Get a book!

PERCENT COMPOSITION

Percentage by mass of elements in a compound –

mass % (weight percent)

Determined by comparing the mass of the

element in 1 mole of the compound to the total

mass of 1 mole of the compound multiplied by

100. Mass percent of element = mass of element in 1 mole of compound x 100 mass of 1 mol of compound

The percentages of each element in the compound should add up to 100% if done

correctly. A way to check your work.

PROBLEMS PAGE 132

71 c & d

73

75

81 c & d

83 b & d

DETERMINING THE FORMULA OF A COMPOUND

Empirical formula-simplest formula for a compound that

shows the atomic ratio of the elements in the compound

Empirical formula lowest whole # ratio

Simplest form

Molecular formula- the actual formula of a molecular

substance that gives the ratio of atoms of each element to

the substances molecules

Molecular formula can be a higher whole # ratio than the

empirical formula must compare the molar mass of the

compound and the mass of the empirical formula you

determined

Sometimes the empirical and molecular formula will be the

same!!!!

HOW TO FIND THE EMPIRICAL FORMULA

FROM % COMPOSITION DATA. 1. Change the % to grams(assume dealing with a

100.0 gram sample)

2. For each element convert the # of grams of each

element into moles using molar mass

3. Get a ratio by dividing all the mole values by the

smallest number of moles

4. Need ratios to be in whole numbers so may need

to multiply to get a whole number-these values will

be the subscripts in our formula

If given grams then skip step one to determine the

empirical formula.

DETERMINING THE MOLECULAR FORMULA

Obtain empirical formula

Compute the mass that corresponds to that formula

Calculate the ratio

Molar Mass (given to you) = x

Empirical formula Mass

Multiply the empirical formulas subscripts by

“x” to get the molecular formula (can be 1)

PROBLEMS PAGE 133

85 a & b

87

89

93

95

CHEMICAL REACTIONS

Reactions involve chemical changes in matter

resulting in new substances.

Reactions involve rearrangement and

exchange of atoms to produce new

molecules.

Reactants Products

CHEMICAL EQUATIONS

Shorthand way of describing a reaction

Provide information about the reaction

Formulas of reactants and products

States of reactants and products

Relative numbers of reactant and product

molecules that are required

Can be used to determine weights of reactants

used and products that can be made

COMBUSTION OF METHANE

Methane gas burns to produce carbon dioxide gas and gaseous water.

Whenever something burns it combines with O2(g).

CH4(g) + O2(g) CO2(g) + H2O(g)

If you look closely, you should immediately

spot several problems.

To correct these problems, we must balance

the equation by adding coefficients, not

changing the subscripts.

COMBUSTION OF METHANE, BALANCED

To show the reaction obeys the Law of

Conservation of Mass the equation must be

balanced.

We adjust the numbers of molecules so there

are equal numbers of atoms of each element on

both sides of the arrow.

1 C + 4 H + 4 O 1 C + 4 H + 4 O

Problems 99, 101, 103, 105, 107, and 109.

ORGANIC COMPOUNDS

Early chemists divided compounds into two

types: organic and inorganic.

Compounds from living things were called

organic; compounds from the nonliving

environment were called inorganic.

Organic compounds are easily decomposed

and could not be made in the lab.

Inorganic compounds are very difficult to

decompose, but are able to be synthesized.

MODERN ORGANIC COMPOUNDS

Today organic compounds are commonly

made in the lab and we find them all around

us.

Organic compounds are mainly made of C

and H, sometimes with O, N, P, S, and trace

amounts of other elements

The main element that is the focus of organic

chemistry is carbon.

CARBON BONDING

Carbon atoms bond almost exclusively

covalently.

Compounds with ionic bonding C are generally

inorganic.

When C bonds, it forms four covalent bonds:

4 single bonds, 2 double bonds, 1 triple + 1 single,

etc.

Carbon is unique in that it can form limitless

chains of C atoms, both straight and

branched, and rings of C atoms.

CARBON BONDING

HYDROCARBONS

Organic compounds can be categorizing into

types: hydrocarbons and functionalized

hydrocarbons.

Hydrocarbons are

organic compounds

that contain only

carbon and hydrogen.

Hydrocarbons

compose common

fuels such as

oil,

gasoline,

liquid propane gas,

and natural gas.

HYDROCARBONS

Hydrocarbons containing

only single bonds are

called alkanes,

while those containing

double or triple bonds are

alkenes and alkynes,

respectively.

Hydrocarbons consist of a

base name and a suffix.

alkane (-ane)

alkene (-ene)

alkyne (-yne)

The base names for a

number of

hydrocarbons are listed

here:

1 meth 2 eth

3 prop 4 but

5 pent 6 hex

7 hept 8 oct

9 non 10 dec

NAMING OF HYDROCARBONS

Base name

determined by

number of C atoms

Suffix

determined by

presence of

multiple bonds

COMMON HYDROCARBONS

FUNCTIONALIZED HYDROCARBONS

The term functional group derives from the

functionality or chemical character that a

specific atom or group of atoms imparts to

an organic compound.

Even a carbon–carbon double or triple bond can

justifiably be called a “functional group.”

A group of organic compounds with the

same functional group forms a family.

FUNCTIONALIZED HYDROCARBONS

FAMILIES IN ORGANIC COMPOUNDS

Problems 111, 113, 115, 117

OPTIONAL PROBLEMS FOR EXTRA PRACTICE

60. c & d 83. a & c

61. a & b 86, b & c

62. a & b 88

64. b & c 90

66. a & b 94

68. b & c 98

72. a & b 100 108

74 102 110

78 104

82 c & d 106

ASSIGNMENT

Book Assignment-

(62, 64, 66, 68, 72, 82, 84, 94 a & b only), 74, 76,

78, 86, 88, 90, 100, 102, 104, 106, 108, 110

Rather have worksheets than a book

assignment