Naming Covalent and Ionic Compounds

1. Chemistry: Atoms First
Julia Burdge & Jason Overby
Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Naming Ionic and
Covalent Compounds

2. A compound is a substance composed of two or more elements
combined in a specific ratio and held together by chemical bonds.
Familiar examples of compounds are water and salt (sodium
chloride).
Compounds
5.1

3. Ionic Compounds and Bonding
The resulting electrically neutral compound, sodium chloride, is
represented with the chemical formula NaCl.
The chemical formula, or simply formula, of an ionic compound
denotes the constituent elements and the ratio in which they
combine.

4. A monatomic ion is named by changing the ending of the element’s
name to –ide.
Cl– is chloride O2– is oxide
Some metals can form cations of more than one possible charge.
Fe2+ : ferrous ion [Fe(II)]
Fe3+ : ferric ion [Fe(III)]
Mn2+ : manganese(II) ion
Mn3+ : manganese(III) ion
Mn4+ : manganese(IV) ion
Naming Ions and Ionic Compounds
5.4

5. Naming Ions and Ionic Compounds

6. Naming Ions and Ionic Compounds
Formulas for ionic compounds are generally empirical formulas.
Ionic compounds are electronically neutral.

7. Al3+ O2–
Al2O3
In order for ionic compounds to be electronically neutral, the sum
of the charges on the cation and anion in each formula must be
zero.
Aluminum oxide:
Sum of charges: 2(+3) + 3(–2) = 0
Formulas of Ionic Compounds

8. Formulas of Ionic Compounds

9. Naming Ions and Ionic Compounds
To name ionic compounds:
1) Name the cation
 omit the word ion
 use a Roman numeral if the cation can have more than one
charge
2) Name the anion
 omit the word ion
Examples:
NaCN sodium cyanide
FeCl2 iron(II) chloride
FeCl3 iron(III) chloride

10. Polyatomic ions consist of a combination of two or more atoms.
Formulas are determined following the same rule as for ionic
compounds containing only monatomic ions: ions must combine in
a ratio that give a neutral formula overall.
Calcium phosphate:
Covalent Bonding in Ionic Species
5.7
Ca2+ PO4
3–
Ca3(PO4)2
Sum of charges: 3(+2) + 2(–3) = 0

11. Covalent Bonding in Ionic Species

12. Covalent Bonding in Ionic Species

13. Worked Example 5.9
Strategy Begin by identifying the cation and anion in each compound, and then
combine the names for each, eliminating the word ion.
Name the following ionic compounds: (a) Fe2(SO4)3, (b) Al(OH)3, and (c) Hg2O.
Solution (a) Fe2(SO4)3 is iron(III) sulfate.
(b) Al(OH)3 is aluminum hydroxide.
(c) Hg2O is mercury(I) oxide.
Think About It Be careful not to confuse the subscript in the formula with the
charge in the metal ion. In part (a), for example, the subscript on Fe is 2, but this
is an iron(III) compound.

14. Covalent Bonding in Ionic Species
Oxoanions are polyatomic anions that contain one or more oxygen
atoms and one atom (the “central atom”) of another element.
Starting with the oxoanions that end in –ate, we can name these
ions as follows:
1) The ion with one more O atom than the –ate ion is called the
per…ate ion. Thus, ClO3
- is the chlorate ion, so ClO4
- is the
perchlorate ion.
2) The ion with one less O atom than the –ate ion is called the –ite
ion. Thus, ClO2
- is the chlorite ion.
3) The ion with two fewer O atom than the –ate ion is called the
hypo…ite ion. Thus, ClO- is the hypochlorite ion.
At minimum, memorize the oxoanions that end in –ate so you can
apply these guidelines when necessary.

15. Covalent Bonding in Ionic Species
perchlorate ClO4
-
chlorate ClO3
-
chlorite ClO2
-
hypochlorite ClO-
nitrate NO3
-
nitrite NO2
-
phosphate PO4
3-
phosphite PO3
3-
sulfate SO4
2-
sulfite SO3
2-

16. Worked Example 5.10
Strategy Each species is either an oxoanion or an oxoacid. Identify the
“reference oxidation” (the one with the –ate ending) for each, and apply the rules
to determine appropriate names.
Name the following species: (a) BrO4
-, (b) HCO3
-, and (c) H2CO3.
Solution (a) BrO4
- has one more O atom than the bromate ion (BrO3
-), so BrO4
-
is the perbromate ion.
(b) CO3
2- is the carbonate ion. Because HCO3
- has one ionizable hydrogen atom,
it is called the hydrogen carbonate ion.
(c) With two ionizable hydrogen atoms and no charge on the compound, H2CO3 is
carbonic acid.
Think About It Make sure that the charges sum to zero in each compound
formula. In part (a), for example, Hg2+ + 2Cl- = (+2) + 2(-1) = 0; in part (b),
(+2) + 2(-1) = 0; and in part (c), 3(+1) + (-3) = 0.
Think About It Remembering all these names and formulas is
greatly facilitated by memorizing the common ions that end in –ate.
chlorate ClO3
- nitrate
NO3
-
iodate IO3
-
carbonate CO3
2-
bromate BrO3
- oxalate
C2O4
2-
sulfate SO4
2- chromate
CrO4
2-
phosphate PO4
3- permanganate
MnO4
-

17. Worked Example 5.11
Strategy The –ous ending in the name of an acid indicates that the acid is
derived from an oxoanion ending in –ite. The oxoanion must be sulfite, SO3
2-, so
add enough hydrogen ions to make a neutral formula.
Determine the formula of sulfurous acid.
Solution The formula of sulfurous acid is H2SO3.
Think About It Remembering all these names and formulas is greatly facilitated
by memorizing the common ions that end in -ate.

18. Hydrates
A hydrate is a compound that has a specific number of water
molecules within its solid structure.
For example, in its normal state, copper(II) sulfate has five water
molecules associated with it.
Systematic name: copper(II) sulfate pentahydrate
Formula: Cu(SO)4 ∙ 5H2O
Some other hydrates are
BaCl2 ∙ 2H2O
LiCl ∙ H2O
MgSO4 ∙ 7H2O
Sr(NO3)2 ∙ 4H2O

19. Hydrates
When the water molecules are driven off by heating, the resulting
compound, Cu(SO)4, is sometimes called anhydrous copper(II)
sulfate.
Anhydrous means the compound no longer has water molecules
associated with it.

20. Familiar Inorganic Compounds

21. Covalent Bonding and Molecules

22. A chemical formula denotes the
composition of the substance.
A molecular formula shows the exact
number of atoms of each element in a
molecule.
Some elements have two or more distinct
forms known as allotropes.
 For example, oxygen (O2) and ozone
(O3) are allotropes of oxygen.
A structural formula shows not only the
elemental composition, but also the
general arrangements.
Covalent Bonding and Molecules

23. Molecular substances can also be represented using empirical
formulas, the whole-number ratio of elements.
While, the molecular formulas tell us the actual number of atoms (the
true formula), the empirical formula gives the simplest formula.
Molecular formula: N2H4
Empirical formula: NH2
The molecular and empirical formulas are often the same.
Covalent Bonding and Molecules

24. Covalent Bonding and Molecules

25. Remember that binary molecular compounds are substances that
consist of just two different elements.
Nomenclature:
1) Name the first element that appears in the formula.
2) Name the second element that appears in the formula,
changing its ending to –ide.
Examples:
HCl hydrogen chloride
HI hydrogen iodide
Naming Molecular Compounds
5.6

26. Greek prefixes are used to denote the number of atoms of each
element present.
Naming Molecular Compounds

27. The prefix mono- is generally omitted for the first element.
For ease of pronunciation, we usually eliminate the last letter of a
prefix that ends in “o” or “a” when naming an oxide.
Example: N2O5 is dinitrogen pentoxide not dinitrogen
pentaoxide
Naming Molecular Compounds

28. Worked Example 5.7
Strategy Each compound will be named using the systematic nomenclature
including, where necessary, appropriate Greek prefixes.
Name the following binary molecular compounds: (a) NF3 and (b) N2O4.
Solution (a) nitrogen trifluoride
(b) dinitrogen tetroxide
Think About It Make sure that the prefixes match the subscripts in the
molecular formulas and that the word oxide is not preceded immediately by an
“a” or an “o”.

29. Worked Example 5.8
Strategy The formula for each compound will be deduced using the systematic
nomenclature guidelines.
Write the chemical formulas for the following binary molecular compounds:
(a) sulfur tetrafluoride and (b) tetraphosphorus decasulfide.
Solution (a) SF4
(b) P4S10
Think About It Double-check that the subscripts in the formulas match the
prefixes in the compound names: (a) 4 = tetra and (b) 4 = tetra and 10 = deca.

30. The names of molecular compounds containing hydrogen do not
usually conform to the systematic nomenclature guidelines.
Many are called by the common, nonsystematic names or by names
that do not indicate explicitly the number of H atoms present.
Examples:
B2H6 Diborane
SiH4 Silane
NH3 Ammonia
PH3 Phosphine
H2O Water
H2S Hydrogen sulfide
Compounds Containing Hydrogen

31. Compounds Containing Hydrogen
One definition of an acid is a substance that produces hydrogen
ions (H+) when dissolved in water.
HCl is an example of a binary compound that is an acid when
dissolved in water.
To name these types of acids:
1) remove the –gen ending from hydrogen
2) change the –ide ending on the second element to –ic.
hydrogen chloride → hydrochloric acid

32. Compounds Containing Hydrogen
A compound must contain at least one ionizable hydrogen atom to
be an acid upon dissolving.

33. Our nomenclature discussion so far has focused on inorganic
compounds, generally defined as those without carbon.
Organic compounds contain carbon and hydrogen, sometimes in
combination with other atoms.
Hydrocarbons contain only carbon and hydrogen.
The simplest hydrocarbons are called alkanes.
Organic Compounds

34. Organic Compounds

35. Organic Compounds

36. Organic Compounds
Many organic compounds contain groups of atoms known as
functional groups, which often determine a molecule’s reactivity.

37. A molecule is an aggregate of two or more atoms in a
definite arrangement held together by chemical bonds
H2 H2O NH3 CH4
A diatomic molecule contains only two atoms
H2, N2, O2, Br2, HCl, CO
A polyatomic molecule contains more than two atoms
O3, H2O, NH3, CH4

38. Writing Chemical Formals
One way to remember these
elements is:
Mr. BrINClHOF
There are 7 elements that occur in nature as a diatomic molecule

39. A monatomic ion contains only one atom
A polyatomic ion contains more than one atom
Na+, Cl-, Ca2+, O2-, Al3+, N3-
OH-, CN-, NH4
+, NO3
-

40. 2.5

41. Guidelines for Writing Chemical Formulas
for Binary Compounds
1. Except for Hydrogen, the element farther to the left in the
periodic table appears first. Ie: KCl, PCl3, Al2S3, and Fe3O4
2. If hydrogen is present, it appears last except when the other
element is from group 16 or 17. Ie: LiH, NH3, B2H6, CH4
H2O, HCl and HI
3. If both elements are from the same group, the lower one
appears first. Ie: SiC and BrF3

42. A molecular formula shows the exact number of
atoms of each element in the smallest unit of a
substance
An empirical formula shows the simplest
whole-number ratio of the atoms in a substance
H2O
H2O
molecular empirical
C6H12O6 CH2O
O3 O
N2H4 NH2

43. ionic compounds consist of a combination of cations
and an anions
• the formula is always the same as the empirical formula
• the sum of the charges on the cation(s) and anion(s) in each
formula unit must equal zero
The ionic compound NaCl

44. Formula of Ionic Compounds
Al2O3
2 x +3 = +6 3 x -2 = -6
Al3+ O2-
CaBr2
1 x +2 = +2 2 x -1 = -2
Ca2+ Br-
Na2CO3
1 x +2 = +2 1 x -2 = -2
Na+ CO3
2-

45. M
U
S
T
K
N
O
W
Ion Name (common name) Ion Name (Common name)
NH4
+ Ammonium CO3
2- Carbonate
H3O+ Hydronium HCO3
- Hydrogen carbonate
(bicarbonate)
OH- Hydroxide SO3
2- Sulfite
CN- Cyanide HSO3
- Hydrogen sulfite
NO2
- Nitrite SO4
2- Sulfate
NO3
- Nitrate HSO4
- Hydrogen sulfate
ClO- Hypochlorite (often
written OCl-)
SCN- Thiocyanate
ClO2
- Chlorite S2O3
2- Thiosulfate
ClO3
- Chlorate CrO4
2- Chromate
ClO4
- Perchlorate Cr2O7
2- Dichromate
MnO4
- Permanganate PO4
3- Phosphate
CH3CO
2
-
Acetate (can be written
C2H3O2
-)
HPO4
2- Hydrogen phosphate
C2O4
2- Oxalate H2PO4
- Dihydrogen phospate

46. Recognizing Ionic Compounds
A compound is ionic if it contains a metal from group 1
Or group 2 or one of the polyatomic ions. Binary metal
Oxides and sulfides also have ionic character
Fig 2-23
Pg 59
Pure water(left)
and a solution
of sugar(right)
do not conduct
electricity
because they
contain virtually
no ions. A
solution of salt
(center)
conducts
electricity well
because it
contain mobile
cations and
anions.
Courtesy Ken Karp

47. Chemical Nomenclature
• Ionic Compounds
– often a metal + nonmetal
– anion (nonmetal), add “ide” to element name
BaCl2 barium chloride
K2O potassium oxide
Mg(OH)2 magnesium hydroxide
KNO3 potassium nitrate

48. Cations of Variable Charge
Transition metals such as copper may form cations
Of different charge. This is represented by placing a
Roman numeral after the transition metal in
Parentheses after the name of the metal.
CuO Copper(II) oxide
Cu2O Copper(I) oxide

49. • Transition metal ionic compounds
– indicate charge on metal with Roman numerals
FeCl2 2 Cl- -2 so Fe is +2 iron(II) chloride
FeCl3 3 Cl- -3 so Fe is +3 iron(III) chloride
Cr2S3 3 S-2 -6 so Cr is +3 (6/2) chromium(III) sulfide

50. • Molecular compounds
• nonmetals or nonmetals + metalloids
• common names
• H2O, NH3, CH4, C60
• element further left in periodic table
is 1st
• element closest to bottom of group is
1st
• if more than one compound can be
formed from the same elements, use
prefixes to indicate number of each
kind of atom
• last element ends in ide

51. HI hydrogen iodide
NF3 nitrogen trifluoride
SO2 sulfur dioxide
N2Cl4 dinitrogen tetrachloride
NO2 nitrogen dioxide
N2O dinitrogen monoxide
Molecular Compounds
TOXIC!
Laughing Gas

52. An acid can be defined as a substance that yields
hydrogen ions (H+) when dissolved in water.
HCl
•Pure substance, hydrogen chloride
•Dissolved in water (H+ Cl-), hydrochloric acid
An oxoacid is an acid that contains hydrogen,
oxygen, and another element.
HNO3 nitric acid
H2CO3 carbonic acid
H2SO4 sulfuric acid
HNO3

53. A base can be defined as a substance that yields
hydroxide ions (OH-) when dissolved in water.
NaOH sodium hydroxide
KOH potassium hydroxide
Ba(OH)2 barium hydroxide

54. Hydrates
A hydrate is an ionic compound that has water molecules
Incorporated into their solid structures
Writing the formula: name of ionic compound-# H2O
Pg 89
The Hydrate of copper
sulfate is the pentahydrate,
and the anhydrous copper
sulfate will absorb water
to form the Hydrate.
CuSO4 5 H2O
.
Copper(II)sulfate.pentahydrate
Olmsted Williams

55. Writing Chemical Formulas
For non ionic compounds with more than 2 atoms
Write Carbon first
Hydrogen second
All other elements in alphabetical order
4 Hydrogen
2 Carbons
4 oxygens
1 Fluorine
1 Sulfur
C2H4FlO4S
4 Carbons
1 Bromine
8 Hydrogen
1 Chlorine
2 Nitrogen
4 Oxygens
C4H8BrClN2O4
Let’s try some………………
4 Iodines
6 Carbons
10 Hydrogens
C6H10I4

56. Structural Formulas
for Carbon Containing Compounds
Draw a line to show a connection between all elements in a molecule
Carbon makes 4 connections (this makes them central or inside atoms)
Oxygen and Sulfur make 2
Halogens and Hydrogen make 1 (terminal atoms)
Nitrogen makes 3
Let’s try some…………………
C2H5FlO
(This molecule contains
an alcohol (OH)
H-C-C-O-H
Fl
H
H
H
C4H7ClN (This molecule contains
An amine, NH2)
Cl-C-C-C-C-N
HH
H
H H
H
H
H
H H

57. Line Formulas
for Carbon Containing Compounds
All ends and corners represent a Carbon
Hydrogens on Carbons are NOT shown
All other elements and Hydrogens not on a Carbon are shown
Let’s try some…………………
(It always helps to draw the structural formula first)
C2H5FlO
(This molecule contains
an alcohol (OH)
H-C-C-O-H
Fl
H
H
H
C4H7ClN (This molecule contains
An amine, NH2)
Cl-C-C-C-C-N
HH
H
H H
H
H
H
H H
F
O H
Cl
N
H
H

58. Naming Carbon Compounds
Prefixes for number of carbons
1 Meth-
2 Eth-
3 Prop-
4 But-
5 Pent-
6 Hex-
7 Hept-
8 Oxt-
9 Non-
10 Dec-
If there are only single bonds
The ending is ane
Hydrogens are understood
All other groups attached to a carbon
are listed before the carbon based name
If the compound is circular the
Prefix cyclo is attached
If there is an –OH group attached
The compound ends in ol
Let’s try some problems……………………….