2.4 Nomenclature Notes
Part 1: Basics Concepts Of Chemistry And Naming Compounds
Introductions To Nomenclature:
●
●
●
Chemists use chemical formulas or chemical names to identify specific
compounds
○ Each compound has a unique name
Some compounds have traditional names (e.g. Water, Ammonia, etc)
There is a standard naming system for chemists around the world (IUPAC) to
make it easier to communicate
○ *IUPAC = International Union of Pure and Applied Chemistry
Language Of Chemistry:
●
Chemistry is the study of matter—its properties and interactions
Matter
Pure
Substance
Element
●
●
●
●
Mixture
Compound
Nomenclature: Names and formulas of a compound
Elements = Letters
Compounds = Words
Chemical Equations = Chemical sentences
Elements:
● Made of ONE type of atom (e.g. carbon, aluminum)
● Found on the periodic table and made up of one type of atom (Carbon,
Aluminum, etc)
● 3 Types Of Elements: Metals, non-metal, metalloids
○ Metals give electrons
○ Non-metals gain electrons
○ Metalloids touch the staircase
● Each element has a name and symbols (*memorize these)
Compounds:
● Two or more types of atoms chemically bonded together
○ Ionic - Metal atoms give electrons to non-metal atoms creating positive
and negative ions (ionic bond) Example: NaCl (Sodium Chloride)
○ Molecular - Non-metal atoms share electrons (covalent bond) to make
molecules Example: H2O
Binary Compounds:
●
●
Binary: two types of atoms
○ Always ends in “ide”
There are two types of Binary compounds: Ionic and Molecular compounds
○ Ionic: Metal + Non-Metal
○ Molecular: Non-Metal + Non-Metal
Ionic Compounds
Binary Ionic Compounds: Metal + Non-Metal
Ion charges of main group (1,2,13,-18) elements are found on the periodic table
Ion charges (oxidation numbers) are used to predict chemical formulas
○ Always ends in -ide
● Ion charges are charges an atom receives when it gains/loses electrons
➔ Metals lose ions
➔ Non-Metals gain ions
Naming:
● Metal elements are named first, Non-Metals are named after
● Name of the first element stays the same
● Ending of the second element is changed to “ide”
○ Ex: NaCl = sodium chloride
●
●
Chemical Formula:
● Write the symbol of the first element (metal)
● Write the ionic charge for each element
● Use the criss-cross method, moving the charges to the opposite element
● Simplify and reduce
● Example: potassium sulfide = K2S
Multivalent Metals and Non-Metals
Handling Multivalent Metals:
● Multivalent metals often have more than one oxidation state (copper, tin, iron)
○ Multiple ion charge possibilities:
➔ Example: Copper has a charge of +1 or +2
It can be either Copper(I) Oxide = Cu2O and Copper(II) Oxide = CuO
● Roman numbers represent the ionic charge of the metals
Two different methods of naming Multivalents:
● Stock method:
○ Roman numerals (I, II, III, IV, V) after the metal name
● Classical method:
○ Uses Latin names of elements
○ Metals with the lowest valence end with “ous”
○ Metals with the highest valence end with “ic”
*Latin names with classical endings:
Latin Name
Remove
“um”
ending
Lower
Valence
Lower
Valance
Name (ous)
Higher
Valence
Higher
Valence
Name (ic)
Cuprum (Cu) Cupr
1+
Cuprous
2+
Cupric
Ferrum (Fe)
Ferr
2+
Ferrous
3+
Ferric
Stannum
(Sn)
Stann
2+
Stannous
4+
Stannic
Plumbum
(Pb)
Plumb
2+
Plumbous
4+
Plumbic
Hydrargyru
m
(Hg)
*Mercur
1+
Mercurous
2+
Mercuric
Element Charges To Memorize:
● Iron: Fe +2, +3
● Gold: Au +1, +3
● Lead: Pb +2 +4
● Mercury: Hg
● Zinc: Zn +2
● Tin: Sn +2, +4
● Nickel: Ni +2, +3
● Manganese: Mn +2, +4
● Copper: Cu +1, +2
Molecules:
Molecular Elements: Non-Metal + Non-Metal (Binary)
Naming: Write down the element name
● Gases at room temp
Chemical Formula (Diatomic Molecules):
Seven elements:
*Write down the element symbol then the subscript of “2”
H O Br F I N Cl
Element
Formula
Hydrogen
H2
Oxygen
O2
Bromine
Br2
Fluorine
F2
Iodine
I2
Nitrogen
N2
Chlorine
Cl2
Molecular Compounds: Non-Metal + Non-Metals (Non-Binary)
Naming:
● When naming compounds with two non-metals, use a prefix to indicate the
number of atoms.
○ Put the prefix in front of the element name
○ Exception: Don't use mono on the FIRST element.
● The atom closest to the bottom left corner of the Periodic Table is named first
● The atom closest to the top right is named second
○ Change the ending of the second element to “ide”
Molecular Compounds: Non-Metal + Non-Metals (*different)
Chemical Formula:
● Use the prefix to determine the subscript
● Do not reduce!
● Example: As2S3 = diarsenic trisulfide
Common Names For Molecular Compounds (memorize):
Name
Formula
Ammonia
NH3
Methane
CH4
Water
H2O
Ozone
O3
Prefixes:
#
Prefix
1
Mono
2
Di
3
Tri
4
Tetra
5
Penta
6
Hexa
7
Hepta
8
Octa
9
Nona
10
Deca
Binary
Compound
Metal + NonMetal
Criss-Cross
Charges
HINT:
Always
consider
FIRST if
element
Is a metal or
non-metal
2 Non-Metals
(molecular)
Use Prefixes
Part 2: Chemical Formulas and Nomenclature
Ionic Compounds (continued):
Polyatomic Compounds: Metal + Polyatomic Ion:
● Polyatomic ions are ions that contain more than one type of atom
● Can be + OR - changed
● Will combine with opposite charge ions to make a compound
Tips To Memorize:
● NICK the CAMEL ate a CLAM for SUPPER in PHOENIX
● N = Nitrate, C = Carbonate, Cl = Chlorate, S = Sulfate, P = Phosphate
○ Underlined letter represents symbol of the element
○ Consonants represent number of oxygen atoms presents
○ Vowels Represent number of negative charge
Polyatomic Ions to Know:
*Note: Look for relationships - e.g. bromine and iodine are halogens like chlorine so their
polyatomic ion formula is the same!
Acetate
C2H3O2 - (CH3COO)
Carbonate
CO32-
* Hydrogen Carbonate (Bicarbonate)
HCO3-
Chlorate
ClO3-
* Bromate
BrO3-
* Iodate
IO3-
Chromate
CrO42-
Dichromate
Cr2O72-
Cyanide
CN-
Hydrogen Sulfide
HS-
Hydroxide
OH-
Permanganate
MnO4-
Nitrate
NO3-
Phosphate
PO43-
* Hydrogen Phosphate
HPO42-
* Dihydrogen Phosphate
H2PO4-
Sulfate
SO42-
* Hydrogen Sulfate
HSO4-
Ammonium
NH4+
Thiosulfate
S2O32-
Naming Polyatomic Compounds:
● Do not change endings of polyatomic ions
● Same ionic naming rules apply
Formulas Of Polyatomic Compounds:
● Use criss-cross method
● Do not alter the subscript of the polyatomic ion
● Put the polyatomic in brackets, criss cross the number outside the bracket with
the number outside the bracket
● Simplify if possible
● Remove brackets if subscript is “1” after criss cross (Example: KOH not K(OH)1)
Naming Polyatomic Compounds With Variable Oxygen (Oxy-Compounds):
● Ions with the “ate” ending are called the base ion
● Removing or adding an oxygen changes the name of the formula, but not the
charge!
● Examples:
○ Chlorate
○ Chlorite
○ Hypochlorite
○ Perchlorate
Ion
Foundation For Formula
Base Ion
“ate”
Remove One Oxygen
“ite”
Remove Two Oxygen
“Hypo
Add One Oxygen
“per
ite”
ate”
Ionic Compounds (Hydrates):
● Not all substances are “dry”: many have traces of water (H2O) in them
● Even if we try to evaporate certain substances, some of the water remains
Naming:
● Name the compound normally, followed by
hydrate (Use the appropriate
prefix for the number of water molecules)
Chemical Formula:
● Write the formula for the compound first, followed by a DOT and the number of
water molecules present
● Examples: CuSO4 is known as Copper (II) Sulfate
○
When Hydrated: CuSO4 ● 5H2O
○
Name becomes: Copper(II) Sulfate Pentahydrate
Part 3 Chemical Formulas And Nomenclature
Acids:
●
●
●
Acids are compounds that when dissolved in water release hydrogen ions (H+)
Hydrogen is usually the first element in the chemical formula of an acid
Hydrogen bonds with: single elements (Binary Acids) or polyatomic ions
(Oxyacids)
Note:
● It is important to remember that a compound is not an acid until it is dissolved in
WATER
● The subscript (aq) is used to denote the acid (aq) = aqueous = dissolved in water
● Dry compound: hydrogen bromide = HBr
Solution (in water): hydrobromic acid = HBr(aq)
Binary Acids:
● Acid that is made by dissolving certain gases in water
● Acids always start with hydrogen and acts like a metal
● Binary acids are formed from binary compounds
Naming:
● Same formula as the gas, but different name
○ Hydro____ic acid
Chemical Formula:
● Criss-cross method
○ Hydrogen (H+) is the cation, it acts as a metal and loses an ion
Example: Hydrosulfuric acid = H2S(aq)
Name of Acid
Formula
Hydrochloric Acid
HCl(aq)
Hydrobromic Acid
HBr(aq)
Hydroiodic Acid
HI(aq)
Hydrofluoric Acid
HF(aq)
Hydrosulfuric Acid
H2S(aq)
Oxyacids:
● Contains oxygen + hydrogen + other element
● Oxyacids are name with a variation of the name of the polyatomic ion in the
formula
● All acids with “ate” endings are called “ic” acids
Naming:
● Replace “ate” with “ic acid”
Chemical Formula:
● Combine hydrogen with the corresponding polyatomic ion
➔ Example: H2SO4(aq) = sulfuric acid
Polyatomic Ion
Acid Name
Acid Formula
Nitrate
Nitric Acid
HNO3 (aq)
Chlorate
Chloric Acid
HClO3 (aq)
Sulfate
Sulfuric Acid
H2SO4 (aq)
Carbonate
Carbonic Acid
H2CO3 (aq)
Phosphate
Phosphoric Acid
H3PO4 (aq)
Acetate
Acetic Acid
CH3COOH (aq) or HC2H3O2 (aq)
Chromate
Chromic Acid
H2CrO4 (aq)
Dichromate
Dichromic Acid
H2Cr2O7 (aq)
Oxyacids: (*Derivatives)
● Many oxyacids have different forms
Naming:
● Similar to derivative of polyatomic ions
○ Start with original acid (-ic acid)
○ Add a prefix “per” if there is 1 more oxygen
○ Change suffix “-ic” to “-ous” if there is 1 less oxygen
○ Add prefix “hypo-” and change suffix “-ic” to “-ous” if there are 2 less
oxygen
Chemical Formula:
● Use prefixes and suffixes to determine the correct number of oxygen atoms
Example: HNO2 (aq) = nitrous acid
HNO4 (aq) = pernitric acid
Compounds
Summary
Compo
Binary
Ionic
Metal +
Non-metal
*Crisscross
Molec
ular
2 NonMetals
*Use
Polyato
Commo
n
Polyato
mic Ions
Metal +
Acids
Binary
H + NonMetal
*Hydro_
_ic acid
Oxyaci
ds
H+
Polyatomic
*base =