Naming and Writing
Formulas
Binary – Ionic or covalent
 Binary compounds
(Compounds with just two elements)
ALL Binary compounds have a suffix “IDE”
on the second element name
(hydride, oxide, sulfide nitride…….)
REMEMBER……
Ionic – metal and nonmetal
Covalent – nonmetal and nonmetal
Naming Binary Covalent
compounds
 Numerical prefixes
are used to name
covalent compounds
of two elements
 First element can
have any prefix
EXCEPT mono
 Second element will
always have both a
prefix and a suffix
Number of atoms
1
2
3
4
5
6
7
8
9
10
Prefix
Mono
DiTriTetraPentaHexaHeptaOctaNonaDeca-
Binary Covalent
Binary compounds (Compounds with just two
elements)
H2S
1. Name the first element adding the correct
prefix (IF NEEDED)– di Hydrogen
2. Name the root of the second element,
adding the correct prefix – mono “Sulf”
3. Add the ending “IDE” to the root
dihydrogen monosulfide
What about covalent
compounds?
 Many covalent compounds are named
with prefixes.
 Examples:
 CO2
 SO2
 H 2O 5
Many covalent compounds
are hydrocarbons with
special names
 Examples:
 CH4
 C 2H 6
 C 2H 4
 C 2H 2
Naming Ionic Compounds
Binary compounds (Compounds with just
two elements)
Na2S
1. Name the first element - Sodium
2. Name the root of the second
element – “Sulf”
3. Add the ending “ide” to the root
Sodium Sulfide
ALL binary compounds will end with “ide”. *There is an exception –
compounds with ammonium can also end in “ide”….. Ammonium Bromide
Naming ionic compounds
 The first name is the name of the cation
 Example: CaCl2 has first name calcium
 The last name has the name of the anion.
(Anion names always end in “ide” unless
they are from your polyatomic ion chart.)
 Example: CaCl2 has last name chloride,
so CaCl2 is calcium chloride
Name these ionic
compounds

1. BaF2

2. K2Se

3. CaS

4. AlF3

5. LiH
Atoms and Charges
 Barium Flouride
 BaF2
 Barium 1 atom, +2
 1 x (+2) = +2
 Flourine 2 atoms, -1
 Calcium Phosphide
 Ca3P2
 Calcium 3 atoms, +2

3 x (+2) = +6
 Phosphorous 2 atoms -3
 2 x (-1) = -2

(+2) + (-2) = 0
 Charges balance !
 (+6) + (-6) = 0
 Charges balance !
2 x (-3) = - 6
Ionic Compounds
Some common Cations
Name and Symbol
Ion charge
Cesium ion, Cs
+1
Lithium ion, Li
+1
Potassium ion, K
+1
Rubidium ion, Rb
+1
Sodium ion, Na
+1
Barium ion, Ba
+2
Beryllium ion, Be
+2
Calcium ion, Ca
+2
Magnesium ion, Mg
+2
Strontium ion, Sr
+2
Aluminum ion, Al
+3
Some common Anions
Name and Symbol
Ion charge
Fluorine, F
FluorIDE - 1
Chlorine, Cl
ChlorIDE - 1
Bromine, Br
BromIDE - 1
Iodine, I
IodIDE
-1
Oxygen, O
OxIDE
- 2
Sulfur, S
SulfIDE
-2
Nitrogen, N
NitrIDE
-3
Some cation names must
show their charge
 Transition metals may form several
different cations each with a different
charge because they have more than
one oxidation number
 These cations must have a Roman
Numeral in their name. The Roman
Numeral shows the cation’s charge.
Naming Binary Ionic Using
Transition metals
 1. Identify the cation (IF it is a transition
look at second element)
 2. Identify the oxidation of the second
element.
 3. Multiply oxidation # (of 2nd element) by
# of atoms (for total charges)
 4. Use this total to identify oxidation of
transition metal.
Formulas with transition
metals………..
Fe2O3 - Fe Yikes a transition!
 Look at the element combined with Fe.
 Oxygen forms a -2 ion , if there are 3 atoms
each with a -2 charge there is a total charge of
-6 …….
 So if Iron has 2 atoms, the total charge must
equal +6.
 Then this iron must be have a +3 oxidation #
(+3 X 2 = +6), so it is named Iron (III) Oxide;
Some Transition Metal
Cations
 Ion name
Copper (I)
Copper (II)
Iron (II)
Iron (III)
Nickel (II)
Nickel (III)
Lead (II)
Lead (IV)
Mercury (I)
Mercury (II)
Gold ((I)
Gold (III)
Symbol
Cu +1
Cu +2
Fe +2
Fe +3
Ni +2
Ni +3
Pb +2
Pb +4
Hg +1
Hg +2
Au +1
Au +3
 Ion name
Symbol
Chromium (II)
Cr +2
Chromium (III)
Cr +3
Tin (II)
Sn +2
Tin (IV)
Sn +4
Titanium (II)
Ti +2
Titanium (III)
Ti +3
Titanium (IV)
Ti +4
Manganese (II)
Mn +2
Manganese (III)
Mn +3
Manganese (IV)
Mn +4
Manganese (VI)
Mn + 6
Manganese (VII)
Mn + 7
Ternary compounds contain
3 elements
 Compounds containing polyatomic
ions have charges listed on your
polyatomic ion chart.
Naming non-binary
compounds (polyatomics)
NaNO3
1.Use the first element name
Na - Sodium
2. Add the polyatomic name
CHECK YOUR LIST
NO3 - Nitrate
NaNO3 -
Polyatomic Ion Names
 Most “normal” polyatomic ion names will
have a suffix of ATE
 ATE suffix indicates Oxygen in formula
 ITE suffix – has one less Oxygen atom
than the “normal”
 Add a prefix of HYPO - has two less
Oxygen atoms than “normal”
 Prefix of PER with “normal” – ADD 1
oxygen atom
Example of Polyatomics –
ate – ite –hypo - per
 Note: Oxidation DOES NOT change
 “Regular”
Chlorate - ClO3
 One less Oxygen Chlorite - ClO2
 Two less Oxygen Hypochlorite – ClO
One more Oxygen Perchlorate - ClO4
With transition elements
 You will have to look at oxidation number
of the polyatomic
 Follow “rules” for using transition
elements
Name these…..
 Mg(NO3)2
 Pb(OH)2
 CuCO3
 K3PO4
 NH4Cl
Check your understanding
 ASSIGNMENTS
Naming of Non-Binary Compounds
Naming Compounds (Mixed): Use flow chart
Binary Covalent – prefixes, & IDE suffix
Binary Ionic – NO prefixes, & IDE suffix
Ionic with transitions – Roman Numerals
and IDE suffix
Non-Binary – use polyatomic list
Names of Acids
 1. H in binary (an “ide”) compound = acid
name with prefix “Hydro”
HCl – (Hydrogen chloride) aka
Hydrochloric Acid
 2. H with “ate” polyatomic, use suffix “ic”
HNO3 is nitric acid
3. H with “ite” polyatomic, use suffix “ous”
H2SO3 is sulfurous acid
Writing Formulas
 Binary Covalent
 Binary Ionic
 Binary Ionic (metals with various
oxidation numbers)
 Ternary (with polyatomics)
Writing Formulas
General rules to remember……
1. Ide suffix means only 2 elements
2. Use prefixes for covalent (di, tri,…)
3. Roman numeral IS the oxidation #
4. Ate, ite suffix or Hypo, per prefix : use
the polyatomic list.
 5. REMEMBER – cation always goes first
 6. Reduce when possible





Quick try….
 Write formulas for binary compounds
when given the oxidation number





Na +1 ,
NaCl
Ba +2 ,
+2 X3, &
Ba3N2
Cl -1
N -3
-3 x2 so……………….
With Polyatomics
 REMEMBER – a polyatomic is treated as
one substance with its own charge…….
 Formula for Lithium phosphate
 Lithium +1
Phosphate -3
 Li +1 (PO4) -3
 Least common multiple is 3……
 Li +1 x 3 = +3
(PO4) -3 x1 = -3
 Final formula Li3PO4
Writing Formulas:
Binary Covalent
 Look at prefixes to determine number of
atoms (subscripts)
 Dinitrogen octofluoride

Di means two nitrogen N2
Octo means eight fluorine
F8
Formula
N2F8
Practice writing covalent
formulas
 1. Dinitrogen monoxide

N2O
 2. Carbon tetraphosphide

CP4
 3. Sulfur difluoride

SF2
Ionic Compounds from
name only

1.
2.
3.
4.
What is the chemical formula for
aluminum fluoride?
List symbols & oxidation for each ion
Al +3
F -1
Identify # of atoms to “balance” the formula need total of 3 negative charges to balance
with Al’s 3 positive charges.
Write chemical formula, using subscripts for #
of atoms for a neutral compound…… AlF3
Reduce if possible and leave the charges off
Practice makes perfect only
if you practice perfect!
 Write formulas for:
 Calcium sulfide
 Ca2+ S2
CaS
 Potassium oxide
 K+1
O2
K2O
For Transition metals
 REMEMBER – the roman numeral tells
you the charge (oxidation #)
 Follow previous steps for writing ionic
formulas
 Iron (III) oxide
 This iron has +3 oxidation
 Oxygen has -2
 Formula:
Fe2O3
Practice makes perfect only
if you practice perfect!
 Write formulas for:
 Iron (III) sulfide
 Fe3+ S2
Fe2S3
 Lead (II) phosphide

Pb+2
P3
Pb3P2
More practice
 1. oxalate combined with potassium
K1+
C2O42 K2C2O4
 2. barium bromate
Ba2+ BrO31 Ba(BrO3)2
Check your understanding
 ASSIGNMENTS
Writing formulas:
Binary with charges given
Polyatomic with charges given
Mixed with names only
“Math Skills” workbook # 9
Chemistry workbook mixed
Or - the easy way…..
Use the “criss-cross” method……
aluminum fluoride
 Aluminum has a +3 charge
 Fluorine has a -1 charge
 Cross the two…
+3
-1
Al
F
1 atom
3 atoms
Formula for aluminum fluoride is AlF3
For Polyatomic ions…..
 Use the “criss-cross” method…….
 Calcium nitrate
 Calcium has a +2 charge
Nitrate has a -1 charge
 Cross the two…
+2
Ca
1 atom
-1
(NO3)
2 atoms
Formula for calcium nitrate is Ca (NO3)2