9-1 Notes
Naming Ions
Monatomic Ions
Ionic compounds consist of a positive
ion (a metal) bonded to a negative
ion (a nonmetal)
Ex. KBr
Monatomic ions consists of a single
atom that has lost or gained
electron(s)
Ex. Potassium ion lost an electron, while
the Bromide ion gained an electron
Cations
 Cations are positively charged ions that occur
when atoms lose electrons
 The # of electrons lost will correspond to the
group # on the periodic table
 Ex. Sodium in group 1 will lose 1 electron
 Naming Cations – the name is the same as
the element the ion is formed from
 Ex. Sodium forms the sodium cation
 Identify the cation of the following
elements: Ca, Rb, Al, Li, Sr
Anions
 Anions are negatively charged ions that occur
when atoms gain electrons
 Nonmetals in groups 5-7 form anions
 The charge is determined by subtracting 8 from
the group #
Ex. Oxygen is in group 6, therefore, 6-8 = -2
 Naming Anions – the end of the element’s name
changes to –ide
 Ex. Bromine forms the Bromide anion
 Identify the anions of the following elements: P,
Se, I, F, N
Ions of Transition Metals
 Many of the transition metals form more
than 1 cation
 The charges must be determined from the
number of electrons lost
 Ex. Iron can lose 2 electrons and form Fe2+ or
it can lose 3 electrons and form Fe3+
 See Table 9.2 p. 255
Ions of Transition Metals
 There are 2 ways to name these ions
 1. Stock System – uses roman numerals to indicate
the charge on the ion
Ex. Fe2+ is Iron (II) while Fe3+ is Iron (III)
 2. Classical name – uses the Latin form of the
element and a suffix to indicate the charge
The suffix –ous indicates the lower of the 2 charges
The suffix –ic indicates the higher of the 2 charges
Ex. Fe2+ is the ferrous ion while Fe3+ is the ferric ion
 A few transition metals only form 1 ion and these
are named like all other cations
 Ex. Silver (Ag+), Zinc (Zn2+)
Polyatomic Ions
 Polyatomic ions are composed of more than
1 atom
 Ex. Nitrate (NO3-) consists of both nitrogen
and oxygen
 The names of most polyatomic ions end in
-ite or –ate
 The use of –ite or –ate as the ending
usually depends on the # of Oxygen atoms
in the ion
 Ex. Nitrate (NO3-) has more oxygen atoms
while Nitrite (NO2-) has less oxygen atoms
Polyatomic Ions
 If the formula for a polyatomic ion begins
with an H it includes a H+
The charge is the sum of the two ions
Ex. Hydrogen carbonate (HCO3-) is the sum of H+
and CO32-
 Most polyatomic ions are negatively charged
The 1 exception is NH4+ which is ammonium
 See Table 9.3 p. 257
9-2 Notes
Naming and Writing Formulas for Ionic Compounds
Naming Binary Ionic Compounds
 A binary compound is composed of 2 elements and
can either be ionic or molecular
 1st step in naming an ionic compound is making sure
it is composed of a monatomic metal cation and a
monatomic nonmetal anion
 When naming, simply place the cation name first
followed by the anion name
 Ex. KBr is Potassium bromide, while Na2O is sodium
oxide
 When the cation is a transition metal with more than
1 charge, you must indicate which ion is being used
 Ex. Cu2O is Copper (I) oxide, while CuO is Copper (II)
oxide
Writing Formulas for Binary Ionic
Compounds
 Step 1: Write the symbol of the cation and then
the anion.
 Step 2: Add whatever subscripts are needed to
balance the charges
 Make sure the subscripts are reduced
 There are two methods to balance charges
 1. Find the least common multiple of the charges
 2. The crisscross method: the numerical value of
the charge of each ion is crossed over and
becomes the subscript for the other ion
 Write the formulas for the following: Iron (III)
oxide and Calcium bromide
Compounds with Polyatomic Ions
 Naming ionic compounds with polyatomic
ions is the same as binary compounds
 Write the cation first followed by the anion
 Name the following: LiCN, AgNO3,
(NH4)2C2O4
Compounds with Polyatomic Ions
 Step 1: Write the symbol of the cation and
then the anion.
 Step 2: Add whatever subscripts are needed
to balance the charges
 Step 3 (if needed): If more than 1
polyatomic ion is needed to balance the
charges you must use parentheses
 Ex. Calcium Nitrate
 Write the formulas for the following:
Lithium carbonate & Aluminum nitrite
9-3 Notes
Naming and Writing Formulas for Molecular
Compounds
Review
How do we do the following?
Name Ionic Compounds
Ex. KBr, Na3PO4, Fe(NO3)3
Write Formulas for Ionic Compounds
Ex. Sodium nitride, Ammonium oxide,
Copper (II) nitrite
Naming Binary Molecular Compounds
 Binary molecular compounds are composed
of molecules, not ions, and consist of 2
nonmetals
 Due to various ways of sharing electrons
the same elements can be used to make
different compounds
 Ex. CO and CO2
 How do you name these so you can tell
there is a difference?
Naming Binary Molecular Compounds
 Prefixes are used to represent the number of
atoms of each element that can be found in a
molecular compound
 The Rules:
 1. Confirm the compound is molecular
 2. Name the elements in the order listed in the
formula
 3. Use the appropriate prefix to indicate the # of
each element (see table 9.4 p. 269)
 Exception: Do not use mono- on the 1st element
 4. Change the ending of the 2nd element to –ide
 Name the following: CO, CO2, N2O5, CCl4
Writing Formulas for Molecular
Compounds
 Step 1: Write the correct symbols for the
two elements
 Step 2: Use the prefixes in the name to
determine the subscript of each element in
the formula
 Write the formula for the following:
Dinitrogen tetraoxide, Dihydrogen
monoxide, Phosphorus pentachloride
9-4 Notes
Naming and Writing Formulas for Acids and Bases
Review
How do we do the following?
Name Ionic Compounds
Ex. (NH4)3PO4, Cr(NO2)3
Write Formulas for Ionic Compounds
Ex. Potassium sulfate, Iron (III) oxide
Name Molecular Compounds
Ex. CO2, CCl4
Write Formulas for Molecular Compounds
Ex. Boron Trichloride, Dinitrogen
tetrahydride
Naming Acids
 An acid is a compound that contains 1 or more
hydrogen atoms and produces H+ when dissolved
in water
 The general form of an acid is HnX
 n is the subscript indicating how many Hydrogen
ions are needed
 X is the monatomic or polyatomic anion
Naming Acids – The Rules
 1. If the anion ends in –ide, the acid name will
begin with hydro-. The –ide will be replaced by –ic
and followed by acid
 Ex. HCl
 2. If the anion ends in –ite, the acid name is the
stem of the anion with the suffix –ous and followed
by acid
 Ex. H2SO3
 3. If the anion ends in –ate, the acid name is the
stem of the anion with the suffix –ic and followed
by acid
 Ex. HNO3
 Name the following: HF, HNO2, HMnO4
Writing Formulas for Acids
 Use the rules for writing the names of acids in
reverse to write the formulas for acids
 Remember – add subscripts to balance the
formula
 Ex. Rule 1 – Hydrobromic acid
 Ex. Rule 2 – Phosphorous acid
 Ex. Rule 3 – Sulfuric acid
 Write formulas for the following: Permanganic
acid, Nitrous acid, hydrosulfuric acid
Bases
 A base is an ionic compound that produces
hydroxide ions when dissolved in water
 Naming bases and writing formulas is the same as
any other ionic compound
 Name the following:
Ba(OH)2, KOH
 Write the formulas for the following: Strontium
hydroxide, Copper (II) hydroxide