Nomenclature = Naming and writing of compounds
Oxidation Numbers – the # of e- lost, gained or shared
by an element or a polyatomic ion when forming a
compound… used for formula writing!
 Polyatomic ions – a group of atoms that act as one
ion (keep them together!)
o Oxidation number of a polyatomic ion is the
charge of the ion
o Polyatomic ion sheet is arranged as such
o Common examples
 NH41+ - ammonia, found in windex
 OH1- - found in cleaners like drano, nair,
deordorant
 C2H3O21- - found in vinegar
 NO31- - found in fertilizer
 CO32- - found in antacids
 PO43- - found in fertilizer, some soft
drinks
 Non metals gain e-‘s an have negative oxidation
#’s
 Metals lose e-‘s and have positive oxidation #’s
 Most common oxidation #’s by group #
Group 1
Group 2
Group 3
Group 4
+1
+2
+3
±4
Group 5
Group 6
Group 7
Group 8
-3
-2
-1
0
Oxidation rules for finding oxidation #’s
 Hydrogen is Almost ALWAYS 1+ unless it is the
exception below
o Exception: 1- when bonded with Alkali metals
(NaH, KH, LiH, etc.)
 Oxygen is Almost ALWAYS 2- unless it is the
exception below
o Exception: 1- when bonded as peroxide
(H2O2)
 Group 1 – Na, K, Li is ALWAYS 1+
 Group 2 – Mg, Ca, Be is ALWAYS 2+
 Group 7 – F, Cl, I, Br is ALWAYS 1 Elements in their elemental state always have an
oxid’n # of 0
o Na oxid # = 0
o Cu oxid # = 0
o S oxid # = 0
 Charged elements have the oxid’n # = the charge
in the upper right hand corner.
o Na1+ oxid # = 1+
o Cu2+ oxid # = 2+
o S2- oxid # = 2 All other elements you may have to solve for given
the information above (called oxid’n numbers
backwards)
o Example – K2SO4 (what is the oxidation
number for each element?)
 K = 1+ (rule stated above)
 O = 2- (rule stated above)
 S = ? (many options on the PT so solve)
(create an algebraic equation keeping in mind the # of
each element. The eq’n is equal to what is in the upper
right hand corner. If there is nothing there, it is equal
to 0)
K2SO4
(2 x +1) + (1 x S) + (4 x -2) = 0
2 + 1 x S + -8 = 0
1 x S = 8-2
S= 6+
You try!
 HCO31-, solve for each elements oxid’n #’s
Formula Writing
Does it start with a nonmetal and only have
nonmetals?
 You will need to know the number of each element
to write the formula. Mono is not used on the first
element.
 Prefixes will tell you the number of each element
(on the back of your poly ion sheet)
 Example
o 1 carbon 2 oxygen becomes CO2 (carbon
dioxide)
 If it starts with an H it is an acid and has its own
set of name and rules! (see back of poly ion sheet)
1 mono2 di3 tri4 tetra5 penta-
6 hexa7 hepta8 octa9 nona10 deca-
Does it start with a metal?
 Determine the oxidation number of each element
and its symbol
o If the element is a metal with more than one
oxidation number (d block, Pb, Sn, etc.) you
will need to choose one unless you are told
one. (example Cu 2+, Mo7+)
o Metal groups (without more than one oxid’n
#)
 Group 1 = 1+
 Group 2 = 2+
o Groups with nonmetals use the most common
oxid # for the group
 Group 7 = 1o Polyatomic ions use the charge in the upper
right hand corner
 Always write the element with positive oxid’n #
first. Cross the oxid’n #’s and write them as
subscripts. 1 is implied and never written!!!!!!
o Example – Na1+ and S2- becomes Na2S
o Cu2+ and P3- becomes Cu3P2
 Crossing charges actually balances the positive
and negative charges making the molecule neutral
 If you have more than one polyatomic ion, you
will need to include parentheses.
Mg2+ and OH1- becomes Mg(OH)2
Li+ and OH- becomes LiOH
 If the superscripts are divisible by the same #, you
need to find the smallest whole # ratio. This only
applies with formula starts with a metal.
o Example – Ca2O2 should be written as CaO
o Example – Mo2O4 should be written as MoO2
(divisible by 2)
Formula naming
 Starts with a metal (Group 1, 2, Ag, Zn)
o Metal with a nonmetal
 Name the metal and then name the
nonmetal with changing ending to “-ide”
 Example – NaCl = Sodium Chloride
 Example – ZnH2 = Zinc Hydride
o Metal with a polyatomic ion
 Name the metal and then name the
polyatomic ion from the sheet
 Example – Na2CO3 = sodium
carbonate
 Example – KC2H3O2 = Potassium
acetate
 Starts with a transition metal (metal with more
than one oxid’n # - mostly d block, Sn, Pb, etc)
o Transition metal with a nonmetal
 Name the metal and write the oxidation #
for the metal in Roman numeral form
and then name the nonmetal with
changing the ending to “-ide”
 Example – FeCl3 = Iron(III)Chloride
 Example – Mo2O7 =
molybdenum(VII)Oxide
 Example – CuO = Copper(II)Oxide
 You may have to do oxidation numbers
backwards to determine the correct
roman numeral for the metal.
 Starts with a nonmetal
o Nonmetals only in which case you must use
prefixes (back of poly ion sheet). Last element
will end with “-ide”. Do not use mono for the
first element ever!
 Prefixes are: mono-1, di-2, tri-3, tetra-4,
penta-5, hexa-6, hepta-7, octa-8, nona-9,
deca-10
 Example – CO = carbon monoxide
 Example – N2O5 = dinitrogen
pentoxide
 Starts with a polyatomic ion (only ammonium in
this class)
o Name the polyatomic ion first (ammonium)
and then name the second part. The second
part can be a nonmetal in which case change
the ending to “-ide”. If the 2nd part is a
polyatomic ion, name the ion.
 Example – (NH4)2S = ammonium sulfide
 Example – NH4NO3 = ammonium nitrate
Naming Acids
Acids break into two parts cation (H30+) and an anion
(the negatively charged thing) to become a neutrally
charged compound
Binary Acids




HCl – Hydrochloric Acid = H+ and ClHI – Hydroiodic Acid = H3O+ and IH2S – ?
HF - ?
Called binary acids because they have two elements
bonded to one another to fill their outer shells.
Prefix for binary acids – “Hydro”
Ending for binary acids – changing the anion to have
an ending of “-ic”
Ternary Acids (oxyacids)
Acids that contain some oxygens in their formula. You
will look to the polyatomic ion that is the anion and
change the ending from “-ate” or “-ic”






H2SO4 – Sulfuric Acid
HClO3 – Chloric Acid
H3PO4 – Phosphoric Acid
H2CO3 – Carbonic Acid
HC2H3O2 – Acetic Acid
HNO3 – Nitric Acid
The above are parent acids, what happen if we lose or
gain oxygen’s?
 HClO3 – Chloric Acid, If we gain a single O, then
it becomes HClO4 (Perchloric Acid)
 If we lose an single O, then it becomes HClO2
(Chlorous Acid)
 If we lose two O, then it becomes HClO
(Hypochlorous acid)
 These rules should look familiar to the polyatomic
ion naming rules!
Halogen Oxyacid Families
 Same as the rules above with the chloric acid. We
are just applying them to the other halogens. All
of them start with O3 as your parent.
o HBrO4
o HIO
o HFO2