9-1 NAMING IONS
DAY 2
MAIN IDEAS IaN
Objective
YOU
Apply the rules for
PG.
naming and writing
COMPLETE!
4
formulas for Binary
Compounds &
Polyatomic ionic
compounds.
Key Concepts: You complete!
CHEMICAL NAMES &
FORMULAS
Day 2
NAMING POLYATOMIC IONS
 Remember
that polyatomic ions are
ions formed from more than 1 atom.
Ex. SO42- = sulfate ion made up of 1
sulfur and 4 oxygen atoms.
 The sulfate ion is a tightly bound unit
(the atoms are covalently bonded)

 The
names of most polyatomic ions
end in –ite or –ate.
-ite
-ate
SO32-
Sulfite
SO42-
sulfate
NO2-
Nitrite
NO3-
nitrate
ClO2-
Chlorite
ClO3-
chlorate
NAMING POLYATOMIC IONS, CONT…
 All
anions with names ending in
–ite or –ate contain oxygen.
 When a polyatomic ion formula begins
with hydrogen, you can think of it as
hydrogen combining with another
polyatomic ion…

Ex. What is the formula for the hydrogen
sulfite polyatomic ion?
H+
SO32-
HSO3
Remember that we are creating the formula
NAMING POLYATOMIC
IONS, CONT…
 Ex.
What is the formula of the
hydrogen phosphate ion?
H+
PO43HPO42-
Ex. What is the formula of the
hydrogen sulfite ion?
H+
SO32HSO3-
BINARY IONIC COMPOUNDS
 Antione
Laurent de Lavoisier (17431794) recognized the need for a
systematic naming system for ionic
compounds. Random naming was
getting out of hand and told nothing of
compound compositions.

Ex. Gypsum, lye, baking soda, potash
These words tell nothing about what these
substances are made of…
Gypsum = CaSO4•2H2O
Lye = NaOH
Baking soda = NaHCO3
potash = K2CO3
NAMING BINARY IONIC COMPOUNDS
 1st – determine that your compound is an
ionic compound.

Ex. Cs2O
Composed of 2 cesium atoms and 1 oxygen
atom
Cs+
O2Cs2O
An ionic compound:


 To
Composed of a metal and a nonmetal
Balanced charge
name the compound, list the cation
first and put an –ide ending on the anion.

Ex. Cs2O is cesium oxide
Now
try these…
 NaBr
 SrF2
 MgO
 LiCl
 H2S
 CaCO3