Chapter 6
Chemical Names and
Formulas
Section 6.1
Introduction to Chemical
Bonding
 OBJECTIVES:
 Distinguish
between ionic and molecular
compounds.
Section 6.1
Introduction to Chemical
Bonding
 OBJECTIVES:
 Define
cation and anion, and relate
them to metal and nonmetal.
Molecules and Molecular
Compounds
 About
100 different elements
 Millions of compounds from them
 Naming is essential in chemistry
 Noble gases, such as He and Ne
 Isolated atoms- monatomic, they
consist of single atoms
Molecules and Molecular
Compounds
 Molecule-
smallest electrically neutral
unit, still has properties of the
substance
 Made from only nonmetals
 Can be from one element- O2
 Can make a compound- CO2
Molecules and Molecular
Compounds
 Properties
of molecular compounds
 Low melting and boiling points
 Usually gas or liquid
 Composed of two or more
nonmetals
 O2, O3, H2O
Systematic Naming
 There
are too many compounds to
remember the names of them all.
 Compound is made of two or more
elements.
 Put together atoms.
 Name should tell us how many and
what type of atoms.
Atoms and ions
Atoms are electrically neutral.
 Same number of protons and electrons.
 Ions are atoms, or groups of atoms, with a
charge (positive or negative)
 Different numbers of protons and
electrons.
 Only electrons can move.
 Gain or lose electrons.

Anion
A
negative ion.
 Has gained electrons.
 Nonmetals can gain electrons.

Charge is written as a superscript on the
right.
F
Has gained one electron (-ide
is new ending= fluoride)
2O
Gained two electrons (oxide)
Cations
 Positive
ions.
 Formed by losing electrons.
 More protons than electrons.
 Metals can lose electrons
+
K
2+
Ca
Has lost one electron (no
name change for positive ions)
Has lost two electrons
Ionic Compounds
 Ionic
compounds- from joining metal
cations and nonmetal anions- they
are electrically neutral
 Usually solid crystals
 Melt at high temperatures
Two Types of Compounds
 Molecular compounds
 Made
of molecules.
 Made by joining nonmetal atoms
together into molecules.
Two Types of Compounds
 Ionic Compounds
Made of cations and anions.
 Metals and nonmetals.
 The electrons lost by the cation are
gained by the anion.
 The cation and anions surround each
other.
 Smallest piece is a FORMULA UNIT.

Two Types of Compounds
Smallest
piece
Types of
elements
State
Melting
Point
Ionic
Molecular
Formula Unit
Molecule
Metal and
Nonmetal
Nonmetals
solid
Solid, liquid
or gas
High >300ºC
Low <300ºC
Section 6.2
Representing Chemical
Compounds
 OBJECTIVES:
 Distinguish
among chemical formulas,
molecular formulas, and formula units.
Section 6.2
Representing Chemical
Compounds
 OBJECTIVES:
 Use
experimental data to show that a
compound obeys the law of definite
proportions.
Chemical Formulas
 Shows
the kind and number of atoms
in the smallest piece of a substance.
 Molecular formula- number and kinds
of atoms in a molecule.
 CO2
 C6H12O6
Chemical Formulas
than one atom? –use a
subscript (H2O)
 There are 7 diatomic elements
 Hydrogen (H2), Nitrogen (N2),
Oxygen (O2), Fluorine (F2),
Chlorine (Cl2), Bromine (Br2), and
Iodine (I2)
 Remember: “Br I N Cl H O F”
 More
Ionic Compounds
 This
formula represents not a
molecule, but a formula unit
 The smallest whole number ratio of
atoms in an ionic compound.
 Ions surround each other so you can’t
say which is hooked to which. (p.
140)
Some Laws:
 1.
Law of Definite Proportions- in a
sample of a chemical compound, the
masses of the elements are always in
the same proportions.
 H2O (water) and H2O2 (hydrogen
peroxide)
Some Laws:
 2.
Law of Multiple ProportionsDalton stated that whenever two
elements form more than one
compound, the different masses of
one element that combine with the
same mass of the other element
are in the ratio of small whole
numbers.
 Figure 6.11, p. 141
Section 6.3
Ionic Charges
 OBJECTIVES:
 Use
the periodic table to determine the
charge on an ion.
Section 6.3
Ionic Charges
 OBJECTIVES:
 Define
a polyatomic ion, and give the
names and formulas of the most
common polyatomic ions.
Charges on ions
 For
most of the Group A elements,
the Periodic Table can tell what
kind of ion they will form from their
location; monatomic ions
 Elements in the same group have
similar properties.
 Including the charge when they are
ions.
1+
2+
3+ 3- 2- 1-
What about the others?
 Groups
4A and 0 do not usually form
ions (in fact, Group 0 rarely forms
compounds!)
 Many transition metals have more
than one common ionic charge
Naming ions
 Two
methods if more than one
charge is possible:
 1. Stock system – uses roman
numerals in parenthesis to
indicate the numerical value
 2. Classical method – uses root
word with suffixes (-ous, -ic)
Does not give true value
Naming ions
We will use the Stock system.
 Cation- if the charge is always the
same (Group A) just write the name of
the metal.
 Transition metals can have more than
one type of charge.
 Indicate the charge with roman
numerals in parenthesis (Table 6.3,
p.144)

Name these
 Na+
 Ca2+
 Al3+
 Fe3+
 Fe2+
 Pb2+
 Li+
Write Formulas for these
 Potassium
ion
 Magnesium ion
 Copper (II) ion
 Chromium (VI) ion
 Barium ion
 Mercury (II) ion
Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluorine

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluorin

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluori

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluor

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluori

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluorid

Naming Anions
Anions are always the same charge
 Change the element ending to – ide
 F Fluoride

Name these
 Cl N3 Br O2 Ga3+
Write these
 Sulfide
ion
 iodide ion
 phosphide ion
 Strontium ion
Exceptions:
 Some
of the transition metals have
only one ionic charge:
 Do not use roman numerals for
these:
 Silver is always 1+ (Ag+)
 Cadmium and Zinc are always 2+
(Cd2+ and Zn2+)
 Note
Fig. 6.13, p. 145
Polyatomic ions
Groups of atoms that stay together and
have a charge.
 Learn these - Table 6.4, p.147






Acetate C2H3O2
Nitrate NO3Nitrite NO2Hydroxide OH- and Cyanide CNPermanganate MnO4-
Polyatomic ions

Sulfate SO42-

Phosphate PO43-

Sulfite SO32-

Phosphite PO33-

Carbonate CO32-

Ammonium NH4+

Chromate CrO42-

Dichromate
Cr2O72-
Section 6.4
Ionic Compounds
 OBJECTIVES:
 Apply
the rules for naming and writing
formulas for binary ionic compounds.
Section 6.4
Ionic Compounds
 OBJECTIVES:
 Apply
the rules for naming and writing
formulas for ternary ionic compounds.
Naming Binary Ionic Compounds
Binary Compounds - 2 elements.
 Ionic - a cation and an anion.
 To write the names, just name the two
ions.
 Easy with Representative elements (which
are Group A elements)
+
 NaCl = Na Cl = sodium chloride
2+ Br- = magnesium bromide
 MgBr2 = Mg

Naming Binary Ionic Compounds
 The
problem comes with the
transition metals.
 Need to figure out their charges.
 The compound must be neutral.
 same number of + and – charges.
 Use the anion to determine the
charge on the positive ion.
Naming Binary Ionic Compounds
Write the name of CuO
 Need the charge of Cu
 O is 2 copper must be 2+
 Copper (II) oxide
 Name CoCl3
 Cl is 1- and there are three of them = 3 Co must be 3+ Cobalt (III) chloride

Naming Binary Ionic Compounds
Write the name of Cu2S.
 Since S is 2-, the Cu2 must be 2+, so
each one is 1+.
 copper (I) sulfide
 Fe2O3
 Each O is 23 x -2 = -6
 2 Fe must = 6+, so each is 3+.
 iron (III) oxide

Naming Binary Ionic Compounds
Write the names of the following
 KCl
 Na3N
 CrN


Sc3P2

PbO

PbO2

Na2Se
Ternary Ionic Compounds
 These
will have polyatomic ions
 At least three elements
 name the ions
 NaNO3
 CaSO4
 CuSO3
 (NH4)2O
Ternary Ionic Compounds
 LiCN
 Fe(OH)3
 (NH4)2CO3
 NiPO4
Writing Formulas
 The
charges have to add up to
zero.
 Get charges on pieces.
 Cations from name on table.
 Anions from table or polyatomic.
 Balance the charges by adding
subscripts.
 Put polyatomics in parenthesis.
Writing Formulas
 Write
the formula for calcium chloride.
 Calcium is Ca2+
 Chloride is Cl Ca2+ Cl- would have a 1+ charge.
 Need another Cl Ca2+ Cl21- (use criss-cross method)
Write the formulas for these
Lithium sulfide
 tin (II) oxide
 tin (IV) oxide
 Magnesium fluoride
 Copper (II) sulfate
 Iron (III) phosphide
 gallium nitrate
 Iron (III) sulfide

Write the formulas for these
 Ammonium
chloride
 ammonium sulfide
 barium nitrate
Things to look for
 If
cations have ( ), the number in
parenthesis is their charge.
 If anions end in -ide they are probably
off the periodic table (Monoatomic)
 If anion ends in -ate or -ite it is
polyatomic
Section 6.5
Molecular Compounds and
Acids
 OBJECTIVES:
 Apply
the rules for naming and writing
formulas for binary molecular
compounds.
Section 6.5
Molecular Compounds and
Acids
 OBJECTIVES:
 Name
acids.
and write formulas for common
Molecular compounds
 made
of just nonmetals
 smallest piece is a molecule
 can’t be held together because of
opposite charges.
 can’t use charges to figure out how
many of each atom
Molecular are easier!
 Ionic
compounds use charges to
determine how many of each.
Have to figure out charges.
Have to figure out numbers.
 Molecular compounds name tells you
the number of atoms.
 Uses prefixes to tell you the number
Prefixes (Table 6.5, p.159)
1 = mono 2 = di 3 = tri 4 = tetra 5 = penta 6 = hexa 7 = hepta 8 = octa
Prefixes
9 = nona 10 = deca To write the name, write two words:

Prefixes
9 = nona 10 = deca To write the name, write two words:

Prefix name Prefix name -ide
Prefixes
9 = nona 10 = deca To write the name, write two words:

Prefix name Prefix name -ide

One exception is we don’t write mono- if
there is only one of the first element.
Prefixes
9 = nona 10 = deca To write the name, write two words:

Prefix name Prefix name -ide
One exception is we don’t write mono- if
there is only one of the first element.
 No double vowels when writing names
(oa oo)

Name These
 N2O
 NO2
 Cl2O7
 CBr4
 CO2
 BaCl2
Write formulas for these
 diphosphorus
pentoxide
 tetraiodine nonoxide
 sulfur hexafluoride
 nitrogen trioxide
 carbon tetrahydride
 phosphorus trifluoride
 aluminum chloride
Acids
Writing names and Formulas
Acids
 Compounds
that give off hydrogen
ions when dissolved in water.
 Must have H in them.
 will always be some H next to an
anion.
 The anion determines the name.
Naming acids
 If
the anion attached to hydrogen
ends in -ide, put the prefix hydro- and
change -ide to -ic acid
 HCl - hydrogen ion and chloride ion
 hydrochloric acid
 H2S hydrogen ion and sulfide ion
 hydrosulfuric acid
Naming Acids
If the anion has oxygen in it, then it
ends in -ate of -ite
 change the suffix -ate to -ic acid (use no
prefix)
 HNO3 Hydrogen and nitrate ions
 Nitric acid
 change the suffix -ite to -ous acid
 HNO2 Hydrogen and nitrite ions
 Nitrous acid

Name these
 HF
 H3P
 H2SO4
 H2SO3
 HCN
 H2CrO4
Writing Acid Formulas
 Hydrogen
will always be first
 name will tell you the anion
 make the charges cancel out.
 Starts with hydro?- no oxygen, -ide
 no hydro?, -ate comes from -ic, -ite
comes from -ous
Write formulas for these
 hydroiodic
 acetic
acid
acid
 carbonic acid
 phosphorous acid
 hydrobromic acid
Section 6.6
Summary of Naming and
Formula Writing
 OBJECTIVES:
 Use
the flowchart in Figure 6.21 to write
the name of a compound when given its
chemical formula.
Section 6.6
Summary of Naming and
Formula Writing
 OBJECTIVES:
 Use
the flowchart in Figure 6.23 to write
a chemical formula when given the
name of a compound.
Helpful to remember...
1. In an ionic compound, the net ionic
charge is zero (criss-cross method)
2. An -ide ending generally indicates a
binary compound
3. An -ite or -ate ending means there
is a polyatomic ion that has oxygen
4. Prefixes generally mean molecular;
they show the number of each atom
Helpful to remember...
5. A Roman numeral after the name of
a cation shows the ionic charge of
the cation
the handout sheets provided
by your teacher!
 Use
Summary of Naming and
Formula Writing
 For
naming, follow the flowchart- Fig.
6.21, page 161
 For writing formulas, follow the
flowchart from Fig. 6.23, p. 162