IONIC COMPOUNDS

 There are 2 forms bonding atoms:
 Ionic —complete transfer of 1 or more electrons from one atom to another (one loses, the other gains)
 Covalent —(molecular) some valence electrons shared between atoms

Let’s Practice!
Sodium loses an electron Na  __________
Magnesium loses two electrons Mg  __________
Chlorine gains one electron Cl  __________
Phosphorus gains three electrons P  __________

-positively charged ion
electrons were lost
We are positive about metal cats!
metals tend to form cations
-name of monatomic cation is the same as the element

Examples:
Na  Na + + e -
Ca  Ca 2+ + 2e -
Fe  Fe 3+ + 3e -

negatively charged ion
-electrons were gained
We feel negatively about ants!
nonmetals tend to form anions
-name of monatomic anion ends in –ide
Cl + e

Cl
-
O + 2e

O
2-
N + 3e

N
3-

Ionic compound-
-composed of cations and anions
-usually metal & nonmetal
-electrically neutral
-mostly solids at room temperature
-high melting points
-the more positive element always comes first
-Ex NaCl, NaF, CaCl
2

Formulas of Ionic Compounds
Formulas of ionic compounds are determined from the charges on the ions
Na
 atoms
+
 ions
   
–
F :

Na + : F :

NaF
    sodium + fluorine sodium fluoride formula
Charge balance: 1+ 1= 0

Monatomic Ions
The charge of a monatomic ion can often be determined by the element’s position on the periodic table:
Group 1A: 1+ Ex. Na +
Group 2A: 2+ Ex. Ca 2+
Group 3A: 3+ Ex. Al 3+
Group 5A: 3Ex. N 3-
Group 6A: 2Ex. O 2-
Group 7A: 1Ex. F -
See Table 6-2 (pg 143)

Alkali metals have a charge of +1
Alkaline Earth metals have a charge of +2
The carbon family has a charge of +
The nitrogen or -4 family has a
The oxygen family has a and are inert
Transition metal charges will need to be memorized!

Elements in Group 0 (8) do not form ions.
Elements in Group 4 rarely form ions.
They tend to react by sharing electrons
(forming covalent compounds) instead of transferring electrons.
Group 8 Electron configuration = s 2 p 6
Group 4 Electron configuration = s 2 p 2

What causes the charges for each group on the periodic table?
 The charges indicate how many electrons an atom will gain or lose.
 If it loses 2, the charge will be +2. If it gains 2, the charge will be -2. Remember that electrons are NEGATIVE!

 The goal of an atom is to become stable.
An atom will gain, lose, or share electrons in order for that stability to be attained.
 Stability is determined by the octet rule:
 Most atoms want 8 valence (outer shell) electrons in order to become stable.

• Ex: Potassium (and all of group 1) has 1 valence electron, so it will lose 1 electron making its charge +1.
Remember that electrons are
NEGATIVE!

Examples:
 O 2-
 P 3-
 F 1-
 Na 1+
 Mg 2+
 Al 3+
 Sr 2+

Quick Check Quiz: Have you been studying your ions?
Na +
O 2-
Se 2selenide _______
Sn 4+

Formula unitchemical formula written for an ionic compound.
-lowest whole-number ratio of ions in the compound

Writing a Formula
Write the formula for the ionic compound that will form between Ba 2+ and Cl

.
Solution:
1. Balance charge with + and – ions
2. Write the positive ion of metal first, and the negative ion Ba 2+ Cl

Cl 
3. Write the number of ions needed as subscripts BaCl
2

Learning Check
Write the correct formula for the compounds containing the following ions:
1. Na + , S 2a) NaS
2. Al 3+ , Cl b) Na
2
S c) NaS
2 a) AlCl
3
3. Mg 2+ , N 3b) AlCl a) MgN b) Mg
2
N
3 c) Al
3
Cl c) Mg
3
N
2

Solution
1. Na + , S 2b) Na
2
S
2. Al 3+ , Cl a) AlCl
3
3. Mg 2+ , N 3c) Mg
3
N
2

Common Names
 A lot of chemicals have common names as well as the proper
IUPAC name.
 Chemicals that should always be named by common name and never named by the IUPAC method are:
 H
2
O water, not dihydrogen monoxide
 NH
3 ammonia, not nitrogen trihydride

Naming Compounds
Binary Ionic Compounds:
 Cation first, then anion
 Monatomic cation = name of the element
 Ca 2+ = calcium ion
 Monatomic anion = root + -ide
 Cl

= chlor ide
 CaCl
2
= calcium chlor ide

Naming Binary Ionic Compounds

Examples:
NaCl sodium chloride
ZnI
2 zinc iodide
Al
2
O
3 aluminum oxide

Learning Check
Complete the names of the following binary compounds:
Na
3
N sodium ________________
KBr potassium ________________
Al
2
O
3
MgS aluminum ________________
_________________________

Solution
Complete the names of the following binary compounds:
Na
3
N
KBr sodium nitride potassium bromide
Al
2
O
3 aluminum oxide
MgS magnesium sulfide

Transition Metals
Elements that can have more than one possible charge MUST have a Roman Numeral to indicate the charge on the individual ion.
1+ or 2+ 2+ or 3+
Cu + , Cu 2+ Fe 2+ , Fe 3+ copper(I) ion iron(II) ion copper (II) ion iron(III) ion

Exceptions:
Zinc and Cadmium will always be
2+ and Silver will always be 1+.

The mercury(I) ion is unique. It only exists in pairs of mercury(I) ions (like Siamese twins). Its symbol is Hg
2
2+ .

Names of Variable Ions
These elements REQUIRE Roman Numerals because they can have more than one possible charge: anything except Group 1A, 2A, Ag, Zn, Cd, and Al
(You should already know the charges on these!)
Or another way to say it is: Transition metals and the metals in groups 4A and
5A (except Ag, Zn, Cd, and Al) require a Roman Numeral.
FeCl
CuCl
SnF
4
PbCl
2
Fe
2
S
3
3
(Fe 3+ )
(Cu + )
(Sn 4+ )
(Pb 2+ )
(Fe 3+ ) iron (III) chloride copper (I) chloride tin (IV) fluoride lead (II) chloride iron (III) sulfide

Examples of Older Names of Cations formed from Transition Metals
(you do not have to memorize these)

Learning Check
Complete the names of the following binary compounds with variable metal ions:
FeBr
CuCl
2 iron (_____) bromide copper (_____) chloride
SnO
2
Fe
2
O
3
Hg
2
S
___(_____ ) ______________
________________________
________________________

Solution
Complete the names of the following binary compounds with variable metal ions:
FeBr
2 iron ( II ) bromide copper ( I ) chloride CuCl
SnO
2 tin (IV) oxide iron (III) oxide Fe
2
O
3
Hg
2
S mercury (I) sulfide

Polyatomic Ions
-tightly bound groups of atoms that behave as a unit and carry a charge
-atoms are bound together by shared electrons

The only positively charged polyatomic ion that we need to memorize is ammonium, NH
4
+ .

Ions that end in –ite or –ate contain oxygen. In a series such as sulfate and sulfite, the –ite ending has one less oxygen than the –ate ending.
Sulfite SO
3
2-
Sulfate SO
4
2-

SO
3
2-
SO
4
2-
NO
2
-
NO
3
sulfite sulfate nitrite nitrate

3
-
2
-

Ternary Ionic Nomenclature
Writing Formulas
 Write each ion, cation first. Don’t show charges in the final formula.
 Overall charge must equal zero.
 If charges cancel, just write symbols.
 If not, use subscripts to balance charges.
 Use parentheses to show more than one of a particular polyatomic ion.
 Use Roman numerals indicate the ion’s charge when needed (stock system)

Ternary Ionic Nomenclature
Sodium Sulfate
Na + and SO
Na
2
SO
4
4
-2
Iron (III) hydroxide
Fe +3 and OH -
Fe(OH)
3
Ammonium carbonate
NH
4
+ and CO
3
–2
(NH
4
)
2
CO
3

Learning Check
1. aluminum nitrate a) AlNO
3 b) Al(NO)
3
2. copper(II) nitrate a) CuNO
3 b) Cu(NO
3. Iron (III) hydroxide
3
)
2 a) FeOH b) Fe
3
OH
4. Tin(IV) hydroxide a) Sn(OH)
4 b) Sn(OH)
2 c) Al(NO
3
)
3 c) Cu
2
(NO
3
) c) Fe(OH)
3 c) Sn
4
(OH)

Solution
1. aluminum nitrate c) Al(NO
3
)
3
2. copper(II) nitrate b) Cu(NO
3
)
2
3. Iron (III) hydroxide c) Fe(OH)
3
4. Tin(IV) hydroxide a) Sn(OH)
4

Naming Ternary Compounds
 Contains at least 3 elements
 There MUST be at least one polyatomic ion
(it helps to circle the ions)
 Examples:
Na NO
3
Sodium nitrate
K
2
SO
4
Al (HCO
3
)
3
Potassium sulfate
Aluminum bicarbonate or
Aluminum hydrogen carbonate

Learning Check
Match each set with the correct name:
1.
Na
2
CO
3
MgSO
3
MgSO
4 a) magnesium sulfite b) magnesium sulfate c) sodium carbonate
2 .
Ca(HCO
3
)
2
CaCO
3
Ca
3
(PO
4
)
2 a) calcium carbonate b) calcium phosphate c) calcium bicarbonate

Solution
1.
Na
2
CO
3
MgSO
3
MgSO
4 c) sodium carbonate a) magnesium sulfite b) magnesium sulfate
2.
Ca(HCO
3
)
2
CaCO
3
Ca
3
(PO
4
)
2 c) calcium bicarbonate a) calcium carbonate b) calcium phosphate

Example: sodium chloride
Na +
1 1
Cl -
1
1
= NaCl

magnesium iodide
Mg 2+
1
I -
2
Mg
1
I
2
= MgI
2

magnesium nitride
Mg 2+
3
N 3-
2
Mg
3
N
2

strontium selenide
Sr 2+
2
Se 2-
2
Sr
2
Se
2
= SrSe

rubidium iodide
Rb + I -
RbI
Al 3+ O 2-
Al
2
O
3

When writing formulas containing polyatomic ions, use parentheses around multiple polyatomic ions.
ammonium carbonate
NH
4
+
2
CO
3
2-
1
(NH
4
)
2
CO
3

strontium hydroxide
Sr 2+
1
OH -
2
Sr(OH)
2

calcium nitrate
Ca 2+
1
NO
3
-
2
Ca(NO
3
)
2

aluminum phosphate
Al 3+
3
PO
4
3-
3
AlPO
4

When naming ionic compounds containing a transition metal, don’t forget to include the Roman numeral for the charge.
Ex. FeCl
2 iron(II) chloride
FeCl
3 iron(III) chloride

Metallic Bonds
 Metals are not ionic but share several properties with ionic compounds.
 Metals also form lattices in the solid state, where 8 to 12 other atoms closely surround each metal atom.

Within the crowded lattice, the outer energy levels of metal atoms overlap.
 The electron sea model proposes that all metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electrons.
 The electrons are free to move around and are referred to as delocalized electrons , forming a metallic cation.
 A metallic bond is the attraction of an metallic cation for delocalized electrons.

Electron Sea

 Metallic Bonds
 Metals are malleable because they can be hammered into sheets.
 Metals are ductile because they can be drawn into wires.
 Mobile electrons surrounding positively charged nuclei make metals good conductors of electricity and heat.

Metal Alloys
 An alloy is a mixture of elements that has metallic properties.

Example : Stainless steel, brass, cast iron
 The properties of alloys differ from the elements they contain.

Example : Steel is iron mixed with at least one other element.
Some properties of iron are present, like magnetism, but steel is stronger than iron.

Metal Alloys

•
Two or more nonmetals
•
Low melting point
•
Low boiling point
•
Example CO
2
•
Metal and nonmetals
(except with NH
4
+ )
•
High melting point
•
High boiling point
•
Solid at room temperature
•
Electrically neutral
•
Example NaCl

Which of the following is molecular and which is ionic?
 NaBr
 CO
2
 O
3
 NO
 KCl
 AlBr
3
Ionic
Molecular
Molecular
Molecular
Ionic
Ionic

Acids
 Acids are ionic compounds
 Even though they contain only nonmetals
 They are held together due to the charges of the ions.

Acid Nomenclature
 Acids
 Compounds that form H + in water.
 Formulas usually begin with ‘H’.
 In order to be an acid instead of a gas, binary acids must be aqueous (dissolved in water)
 Ternary acids are ALL aqueous
 Examples:
 HCl
(aq)
– hydrochloric acid
 HNO
3
– nitric acid
 H
2
SO
4
– sulfuric acid

Acid Nomenclature
Binary 
Anion
Ending Acid Name
-ide hydro -(stem)ic acid
-ate (stem)ic acid
Ternary
-ite (stem)ous acid
An easy way to remember which goes with which…
“In the cafeteria, you ATE something IC ky ”

Acid Nomenclature Flowchart
ACIDS start with 'H'
2 elements 3 elements hydro- prefix
-ic ending no hydro prefix
-ate ending becomes
-ic ending
-ite ending becomes
-ous ending

Acid Nomenclature
• HBr
(aq)
• 2 elements, ide
• H
2
CO
3
• 3 elements, -ate
• H
2
SO
3
• 3 elements, -ite
 hydro bromic acid
 carbon ic acid
 sulfur ous acid

Acid Nomenclature
• hydrofluoric acid
• 2 elements 
H + F-
• sulfuric acid
• 3 elements, -ic
• nitrous acid

H + SO
4
2-
• 3 elements, -ous

H + NO
2
-

HF
(aq)

H
2
SO
4

HNO
2

Name ‘Em!
 HI
(aq)
 HCl
 H
2
SO
3
 HNO
3
 HIO
4
Hydroiodic acid
Hydrogen chloride (not aq!)
Sulfurous acid
Nitric acid
Periodic acid

Write the Formula!
 Hydrobromic acid
 Nitrous acid
 Carbonic acid
 Phosphoric acid
 Hydrotelluric acid
HBr
(aq)
HNO
2
H
2
CO
3
H
3
PO
4
H
2
Te
(aq)