Naming Ions
9.1 and 9.2
Review: cations and anions
 Ions are formed by the gain or loss of electrons
 Metallic elements tend to LOSE electrons, forming
positive ions (cations)
 Group 1 loses 1 electron ex) Li+, Na+, K+, etc
 Group 2 loses 2 electrons ex) Mg+2, Ca+2
 What does group 13 do?
 Non-metals tend to GAIN electrons, forming negative ions
(anions)
 Group 16 gains 2 electrons ex) O-2, S-2
 Group 17 gains 1 electron ex) F-, Cl What does group 15 do?
What about the rest?
 Group 14 elements generally do not form ions
 C and Si are found in Molecular Compounds
 Group 18 (Noble Gases) do not bond
 Transition Metals (along with Sn and Pb) can have
more than one common ionic charge. DANGER
ZONE!
 The Stock System
 Include the charge in the name in roman numerals
 Ex. Fe2+ is called Iron (II) ion
 Fe3+ is called Iron (III) ion
 Classical Names
 The root word + the ending –ous for the lower of the 2
ionic charges or –ic for the higher of the two ionic
charges
 Ex. Iron (ferrum in Latin)
 Fe2+ is called the ferrous ion
 Fe3+ is called the ferric +ion
 -ic > -ous
Use the name to tell you which cation
has the larger or smaller charge
You should memorize the
ions for copper and
iron.
Transition Metal exceptions
 These only have one charge. They do
not require roman numerals.
 Silver = Ag+
 Cadmium = Cd2+
 Zinc = Zn2+
 Aluminum = Al3+
Practice
 Write the symbol with charge. Identify as
cation or anion.
 Lead, 4 electrons lost
 Iodide
 Sulfide
 Manganese, 6 electrons lost
Polyatomic Ions
Polyatomic Ions: Tightly bound groups of atoms
that behave as a unit and carry a charge
“Mutants” of the bonding world.
 Have covalent (sharing) bonds but…
 End up w/ more or less electrons that you would
expect
 Cannot be broken into separate parts
Polyatomic Ions: See Chapter 9 post for which ones
you need to memorize….
You have 2o
ions to
memorize. You
need to know the
name,
symbol, and
charge
.
See Message
from
Mrs. C
announcements
for your quiz date.
Polyatomic Naming Info
 Most names end in –ate or –ite
 -ite has one less oxygen than –ate
 Sulfite SO32-, Sulfate SO42 Nitrite NO2- vs. Nitrate NO3 SAME CHARGE DIFFERENT OXYGEN COUNT
 I got sick from something I ate
 Ic and ate have the higher charge number and
oxygen count respectively.
Some don’t end with –ite or -ate
 Ammonium (NH4+)
 Cyanide (CN-)
 Hydroxide (OH-)
 (Always some pesky exceptions to the rule…)
What about the ions with hydrogen?
 When the formula begins in H (ex. HCO3-) imagine
the H is a hydrogen ion (H+) combined with
another polyatomic ion
 H+ + CO32- → HCO3- (Hydrogen Carbonate)
 Notice how the charges add together to create
the final charge of the polyatomic ion
 Show the formulas for the formation of HPO42and H2PO4- from two different ions just like we did
above.
 H+ + PO43- → HPO42- (Hydrogen Phosphate)
 H+ + PO33- → HPO32- (Hydrogen Phosphite)
 H+ + H+ + PO43- → H2PO4- (Dihydrogen Phosphate)