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Chemical Nomenclature
(a.k.a. naming compounds)
Antoine Lavoisier (1743-1794)
“Father of Modern Chemistry”
• Major contributions included– Established the Law of Conservation of Mass– Introduced scientific experimenting via the BALANCE– Invented a system of chemical nomenclature (still used
in part today!)
– Wrote the 1st modern chemical textbook– Introduced the the 1st 33 elements.– Demonstrated that water cannot be transmuted to
earth– AND MORE …
Types of Compounds The Two main types are:
• Ionic– Made up of ions (both positive and negative charge)
– Must have no net charge (i.e. combined charge of zero)
– Depend on the attraction between positive and negative charges of the ions
– Usually a metal is present as a cation
• Molecular (or covalent)– Made up of atoms that share their outer electrons– Charge plays no direct role in their formation– Usually combination of two or more nonmetals.
Naming Compounds• Easiest way to identify an ionic compound is
whether or not it has a metal present:– Yes ionic (e.g. CaCl2)
– No covalent (e.g. CCl4)
• Ionic compounds are named using the stock system. (No use of prefixes)
• Covalent compounds require the use of Latin prefixes to indicate the number of each element present in one molecule
Naming Binary CompoundsA “simple” or binary compound is a compound made of
only 2 types of elements • When the first element is a metal:
• The first element (metal) keeps its full name• The non-metal goes by its root with the suffix “-ide” added
to the endExample: NaCl is sodium chloride
• When there are no metals present• Same as above except• Latin prefixes must be used to identify the number of each
element present in the compound
Example: CO2 is carbon dioxide
Ionic Charges & the Stock System– Group 1 metals form 1+ cations (Na+ sodium ion)– Group 2 metals form 2+ cations (Ca2+ calcium ion)– Group 13 metals form 3+ cations (Al3+ aluminum ion)– All other metals (i.e. the transitional metals, Pb, etc.) form more than one
type of cation• Roman numerals must be used to indicate the charge of the cation• Example:
Fe3+ is called iron(III)
FeCl3 is called iron(III) chloride
• Exceptions:Ag+, Cd2+ & Zn2+
– Group 15 nonmetals form 3- anions (N3- nitride ion)– Group 16 nonmetals form 2- anions (O2- oxide ion)– Group 17 nonmetals form 1- anions (Cl- chloride ion)– Group 18 nonmetals do not form ions (Zero charge)
Latin Prefixes for Naming Molecules1) Mono-2) Di-3) Tri4) Tetra-5) Penta-
CCl4 is carbon tetrachloride
6) Hexa-7) Hepta-8) Octa-9) Nona-10) Deca-
C3H8 is tricarbon octahydrideNotes:
1) Prefixes are used when the compound does not have a metal present (or when H is the first element in the formula)
2) Prefixes must be used for every element present in the compound
3) mono- is not used for the first element in a compound name (e.g. carbon dioxide)
Ionic Compounds containing Polyatomic ions
• Some ionic compounds are made up of polyatomic ions
• When you encounter this, do not freak out!!• Become familiar with the polyatomic ions on the
handout
Example: the nitrate ion (NO3-)
• The naming of this type of compound is similar to that for ionic compounds but no change in suffix.
Example: Ca(NO3)2 Calcium Nitrate
Oxy-Ions• Polyatomic Ions containing Oxygen can be
represented a number of different ways.
One less Oxygen in the formula change the suffix is changed from “ate” to “ite”. The ion’s charge, however, does not change.
Ex. (NO3)-1 Nitrate vs. (NO2)-1 Nitrite
If two less Oxygens the prefix “hypo-” is placed in front of the “ite” name.
Ex. (ClO)-1 hypo- Chlorite If one more Oxygen the prefix “per-” is placed in front of
the “ate” name.
Ex. (ClO4)-1 Per Chlorate
Acids– From the Latin term for “sour”{Acids are sour to the taste}
– Acids are substances that donate protons (H+) (usually when dissolved in water)
– Chemical formula usually begins with HExample: hydrochloric acid
HCl(aq) + H2O(l) H3O+ + Cl- (aq)
– Taste bitter– Usually metal containing hydroxides– Substances that accept protons (H+) when dissolved in waterExample: potassium hydroxide
KOH(aq) + H3O+ K+(aq) + H2O (l)
Bases
Naming AcidsLets separate acids into 2 types:
– Acids that contain oxygen– Acids that do not contain oxygen
Naming acids containing oxygen:– For acids containing “-ate” anions:
1. Use root of the anion (for sulfate, SO42-, use sulfur)
2. Add “-ic” suffix then end with “acid”
Example: H2SO4 is sulfuric acid
– For acids with “-ite” anions:1. Use root of the anion (for sulfite, SO3
2-, use sulfur) 2. Add “-ous” suffix then end with “acid”
Example: H2SO3 is sulfurous acid
Naming Acids (cont.)Naming acids not containing oxygen:
– Add “hydro-” prefix to beginning– Use root of the anion (i.e. Cl- use chlor)– Add “-ic” suffix then end with “acid”Example: HCl is hydrochloric acid
Name the following acids:HF
HNO2
HCN
H3PO4
Hydrate Molecules• A hydrate molecule is a ionic compound
that contains water molecules trapped inside the crystalline structure.
The Formula includes a dot followed by the number of water molecules
Ex: Copper(II) Sulfate Pentahydrate
CuSO4 · 5H2O
Hydrate Molecules
The Name of a hydrate molecule would include two separate names.
The name of the ionic compound followed by the term ___hydrate. A Greek Prefix would be used to represent the number of water molecules that are trapped.
CoCl2 · 2 H2O Colbalt(II) Chloride Dihydrate
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