Chapter 9
Chemical Formulas and Names
#1 Simple Ionic Compounds
Concept:
Ionic Formulas are formed from positive and
negative ions.
Naming: First element (metal) keeps its name.
Second element (nonmetal) ends in –ide
Simple Ionic Compounds
You already know:
Positive ions are formed by metals that lost
electrons.
Examples: Na1+ Mg2+ Al3+
Negative ions are formed by nonmetals that
gained electrons.
Examples: Cl1- O2N3Si4-
Simple Ionic Compounds
RULE # 1
The overall charge of ionic compounds must
equal zero.
Examples : Na1+ Cl1Problems: Ca2+Br1Al3+O2-
# 2 Polyatomic Ion Formulas
Concept:
Polyatomic ions are groups of atoms that behave
as one unit.
RULE #2
Treat like single ions in formulas, but must have
parentheses when more than one is used in a
formula.
Examples: Ca2+(NO3) 1-2
(NH4) 1+2O2Problem: Ga3+ (SO4) 2-
Polyatomic Ion Formulas
Fact:
The polyatomic ions are named based on the
atoms that they contain. Those with oxygen
and another nonmetal are often name "____ate"
with the root of the other nonmetal in the blank.
Examples: (NO3)1- is nitrate
(SO4)2- is sulfate
(ClO3) 1- is chlorate
Polyatomic Ion Formulas
Fact:
Those polyatomic ions with one oxygen less
than the "ate" ions are named "----ite" ions.
Examples: (NO2)1- is nitrite
(SO3)2- is sulfite
(ClO2)1- is chlorite
Polyatomic Ion Formulas
Some polyatomic ions contain a regular
polyatomic ion and one or more hydrogen ions.
These ion groups are named hydrogen ____
or bi ______.
Examples: H(CO3)1- is called hydrogen
carbonate or bicarbonate
H(SO4) 1- is called hydrogen sulfate or bisulfate
#3 Transition Metal Compounds
Concept:
Transition metals have electrons in d orbitals and can
donate different numbers of electrons, thus giving
them several different positive charges.
RULE:
These can be determined from the Roman numeral
which is written next to the metal's name.
Example: Cu1+is Copper I
Pb2+is Lead II
A few transition metal ions only have one charge.
Example: Ag1+
Zn2+ Cd2+
#4 - Covalent Compounds
In covalent compounds the charges DO
NOT have to balance. First element keeps
its name. Second element ends in –ide
Use Greek prefixes to identify the number of atoms:
1 – Mono
2 – Di
Example:
3 – Tri
4 – Tetra
diposphorous pentoxide
5 – Penta
P₂0₅
6 – Hexa
7 – Hepta
8 – Octa
9 – Nona
10 - Deca