1. CHAPTER 9: Chemical Names and Formulas
Objectives:
To be able to name ionic and molecular compounds, and acids.
2. To be able to write the formulas of ionic and molecular compounds, and acids.

2. Different Types of Formulas and Names
Ionic compounds
Molecular compounds (molecules)
Acids (a special type of molecule)

3. Ionic Compounds
Monatomic ions are ions of a single atom with a positive or
negative charge resulting from the loss or gain of one or
more valence electrons.
Monatomic cations: Monatomic anions:
Na+, Ca2+ Cl-, N3-
Naming monatomic cations: Naming monatomic anions:
Cations for groups 1, 2, & Anion start with the same
metals have the same name as stem and end with -ide.
the atoms, followed by ion or This is followed by ion or
cation anion.
Na+ is sodium ion or sodium Cl- is chloride ion or
cation chloride anion.

4. Other Names of Monatomic Ions
Ion Symbol Ion Name
Li+ lithium ion (or cation)
Ca2+ calcium ion (or cation)
Al3+ aluminum ion (or cation)
F- fluoride ion (or anion)
O2- oxide ion (or anion)
N3- nitride ion (or anion)
P phosphide ion (or anion)

5. Naming Binary Ionic Compounds
Binary Ionic Compounds are composed of ions of
two elements.
To Name Binary Ionic Compounds, place the cation
name first, followed by the anion name.
Formulas Names
NaCl sodium chloride
CaF2 calcium fluoride
Mg3N2 magnesium nitride
AlP aluminum phosphide
K2Se potassium selenide

6. Polyatomic Ions
Polyatomic ions are ions composed of more than one type of atom (usually nonmentals) covalently bonded.
Examples of Polyatomic ions:
NH PO SO OH-
For naming polyatomic ions, you can use your common ion table to get the name.
Compounds Names
NH4Cl ammonium chloride
Na3PO4 sodium phosphate
Al2(CO3)3 aluminum carbonate
Cu(NO2)2 copper(II) nitrite

7. Naming Ions & Ionic Compounds of Transition Metals
Since some transition metals may have more then one charge, the charges of the cations must be determined and represented when naming transition metal ions and compounds with transition metal ions.
For example, iron is a transition metal and can have two common charges, Fe2+ and Fe3+.
When naming these ions, we use the Stock system which uses Roman numerals in parentheses after the metal name.
If the charge of the metal is not given directly, you must determine it by using the formula given.
Ion Name of Ion Ionic Compound Name of Compound
Fe iron(II) ion FeCl iron(II) chloride
Fe iron(III) ion FeCl iron(III) chloride
Cu copper(I) ion CuF copper(I) fluoride
Pb lead(IV) ion PbI lead(IV) iodide

8. Steps to Writing Formulas of Ionic Compounds
Write the symbols of both ions including their charges remembering that the cation is placed first followed by the anion. sodium oxide Na+ O2-
Crisscross the value of the charges. This will make it so that the charges are balanced.
Na O2-
Rewrite your new formula and make sure the charges cancel each other. Na2O two Na+ = total charge
one O2- = is zero
If the charge is 1- or 1+, leave the number 1 out the formula since it is understood to be there.
5. If necessary, reduce the numbers of each atom by a common denominator since formula units represent the lowest ratio of ions in an ionic compound.
6. If there is more then one polyatomic ion present, use ( ) around the ion and then place the subscript outside of the ( ).

9. Formula Practice: Binary Ionic Compounds
Name of Compound Ions Formula
aluminum iodide Al3+ I- AlI3
calcium phosphide Ca2+ P3- Ca3P2
barium sulfide Ba2+ S2- BaS
rubidium bromide Rb+ Br- RbBr
strontium nitride Sr2+ N Sr3N
copper(II) chloride Cu2+ Cl- CuCl2
chromium(III) oxide Cr3+ O2- Cr2O3

10. Naming Ionic Compounds with Transition Metals
It is necessary to determine the charge of a transition metals that can have more then one charge in order to name it.
This can be done by using the formula given and determining the charge of the anion first.
Remember that the total charges of the anion and cation must cancel each other out.
Formula Ions Name
CuCl Cu+ Cl copper(I) chloride
CuCl2 Cu2+ Cl copper(II) chloride
Fe2O Fe2+ O iron(II) oxide
Fe2O Fe3+ O iron(III) oxide
PbO2 Pb O2- lead(IV) oxide
PbCO3 Pb2+ CO lead(II) carbonate

11. Formula Making: Compounds with Polyatomic Ions
Formula making with polyatomic ions is very similar to what you have learned so far.
Just DON’T forget to use ( ) around polyatomic ions when there is more then one of them!
Names Ions Formula
magnesium sulfate Mg2+ SO MgSO4
ammonium fluoride NH4+ F NH4Cl
lithium carbonate Li CO Li2CO3
calcium nitrate Ca NO Ca(NO3)2
beryllium hydroxide Be OH Be(OH)2

12. Naming Binary Molecular Compounds
When two nonmetals combine, they form a molecular compound whose formula shows the actual number of each kind of atom found in a molecule of the compound.
To name these compounds, we use a similar method to naming ionic cmps (see endings) except we can use prefixes to denote number of each atoms.
Note: when there is only atom of the first element in the compound
mono- is not used before the atom’s name.
Note: when using prefixes with atoms that start with a vowel, the last vowel of the prefix is dropped.

13. Naming Practice: Binary Molecular Cmpds
Formula Name
NH3 nitrogen trihydride
PCl5 phosphorous pentachloride
SeF6 selenium hexafluoride
NO nitrogen monoxide
P2O7 diphophorous heptoxide
C3H8 tricarbon octahydrogen

14. Naming Acids
For now, the acids that we will learn how to name contain hydrogen ions, H+. (formulas start with H)
Naming Rules:
When the anion name ends in -ide, the stem of the anion name begins with the prefix hydro- and ends with -ic. The name is then followed by the word acid.
When the anion name ends in -ite, the anion ends with -ous, followed by the word acid.
When the anion name ends in -ate, the anion name ends with -ic, followed by the word acid.

15. Naming Acids Formula Anion Ending Acid Name HBr -ide hydrobromic acid
HCl -ide hydrochloric acid
HI -ide hydriodic acid
H2S -ide hydrosulfuric acid
H2SO4 -ate sulfuric acid
H2SO ite sulfurous acid
H3PO3 -ite phosphorous acid
H3PO4 -ate phosphoric acid
HClO -ite hypochlorous acid
HClO4 -ate perchloric acid