Chapter 10 & 7A
Ions
Monatomic Ions
Ion Formulas and Names
Ion Vocabulary
• An ion is an atom or group of
atoms that have a charge.
• A cation is a positive ion.
• An anion is a negative ion.
If a neutral atom loses one or more
electrons it becomes a cation.
Na
11 protons
11 electrons
Na+
11 protons
10 electrons
If a neutral atom gains one or more
electrons it becomes an anion.
Cl
17 protons
17 electrons
Cl-
17 protons
18 electrons
Atoms tend to lose and
gain electrons when
they bond with other
atoms in an attempt to
become more stable.
Why is Na+ more stable than Na
• Na = 1s22s22p63s1
Why is Na+ more stable than Na
• Na = 1s22s22p63s1
Lose 1 e• Na+ = 1s22s22p6
Why is Na+ more stable than Na
• Na = 1s22s22p63s1
Lose 1 e• Na+ = 1s22s22p6
• This is isoelectronic with Ne
Why is Clˉ more stable than Cl
• Cl = 1s22s22p63s23p5
Why is Clˉ more stable than Cl
• Cl = 1s22s22p63s23p5
Gain 1 e• Clˉ = 1s22s22p63s23p6
Why is Clˉ more stable than Cl
• Cl = 1s22s22p63s23p5
Gain 1 e• Clˉ = 1s22s22p63s23p6
• This is isoelectronic with Ar
Determine the number of protons and
electrons for each ion and state what noble
gas each is isoelectronic with.
Mg
O
12 protons
12 electrons
8 protons
8 electrons
Mg2+
O2-
___ protons
___ electrons
___ isoelectronic
___ protons
___ electrons
___ isoelectronic
Ionic bonding: Li + O
Why is lithium oxide Li2O
3p+ 2e-1e4n0
1e6e- 2e-
3p+ 2e-1e4n0
Li
Li
1e-
O
3p+ 2e4n0
8e- 2e-
8p+
8n0
8p+
8n0
3p+ 2e4n0
[Li]2+ [
O
]2–
Ion Vocabulary
• A monatomic ion is an atom
with a charge.
• The charge on a monatomic ion
is called an oxidation number.
• A polyatomic ion is a group of
atoms with a charge.
Types of monatomic ions and the
rules for naming them
• The periodic table is useful in naming the monatomic
ions.
Monatomic cations with one oxidation number
• The cations from the periodic table which have a
single oxidation number are as follows: Group 1 (+1),
Group 2 (+2), Ag+, Cd2+, Zn2+, and Al3+.
• These types of ions are named by using the name of
the element followed by the word ion.
• Na+ sodium ion
• Ba2+ barium ion
• Zn2+ zinc ion
• We can use the roman numeral from the periodic table
to identify the oxidation number for these ions.
Monatomic cations with multiple oxidation numbers
• All other cations that are not listed in the previous
category (“cations with one oxidation number”) are
considered to have the possibility of multiple oxidation
numbers.
• These type of ions are named by using the name of the
element followed by a Roman numeral to indicate the
oxidation number.
• Cu2+ copper (II)
• Pb4+ lead (IV)
• Mn7+ manganese (VII)
• It is important to note that the roman numerals in
these names may or may not be the roman numeral
from the periodic table.
• In other words the periodic table is of little or no
help in determining their oxidation numbers.
Negative Monatomic anions
• All anions from the periodic table are
named by changing the ending of the
element’s name to –ide.
• F- fluoride ion
• O2- oxide ion
• N3- nitride ion
• Count back from the noble gases starting
at zero to determine the oxidation number.
Ask Yourself 3 Questions.
Does the name end with:
Ion?
Roman numeral?
-ide?
Name these monatomic ions
•
•
•
•
•
•
Rb+
P3Fe3+
Br‾
Mn4+
Cd2+
Rubidium ion
Phosphide
Iron III
Bromide
Manganese IV
Cadmium ion
Write the formula for these
monatomic ions.
•
•
•
•
•
•
Sulfide
Lead (II)
Barium ion
Chromium (IV)
Aluminum ion
Carbide
S2Pb2+
Ba2+
Cr4+
Al3+
C4-
Atoms of elements and Ions of
elements are different
Atoms of elements
Sodium is a soft, silvery highly reactive
metal. It is used in making light bulbs
and for heat exchange in nuclear
reactors.
A pale yellow-green gas, chlorine
killed soldiers in WWI. Today it
primarily used to kill bacteria in
water.
Ions of elements
Combined together sodium and chlorine make common
table salt and are thus essential to life. Table salt
consists of sodium ions (Na+) and chloride ions (Cl-)
Steps for Naming Ions
1. Name polyatomic ions.
2. -ide, ion, Roman numeral?
• Name remaining anions (change ending to
–ide)
• Name remaining cations from groups 1, 2,
Ag+, Cd2+, Zn2+, Al3+. (use the name of the
element and add “ion”)
• Name all remaining cations using the name
of the element followed by a roman numeral
equal to the positive charge of the cation.
1.
2SO4
2. O
2-
7. Cu+
2+
3. Mg
4. Pb
6.
+
Ag
8. NH4+
2+
9.
3P
5. NO2
-
10.
3+
Cl
Steps for Writing Formulas of Ions
•
1.
2.
3.
4.
Many people find that they wish to do these in the
order that they are presented. You can however use
the following order if you find it helpful
Polyatomic ions.
Remaining anions. (These will be anything left that
ends in –ide).
Remaining ions containing a Roman Numeral.
Remaining ions without a Roman Numeral. (get
the roman numeral from the table).
1. Cobalt (I) ion
6. Hydroxide ion
2. Selenide ion
7. Cadmium ion
3. Phosphite ion
8. Lithium ion
4. Nitrogen (V) ion
9. Calcium ion
5. Arsenide ion
10. Mercury (I) ion
Homework
• Worksheet: Ions