Title: Nomenclature
1Nomenclature
- Honors Chemistry
- Mrs. Partridge
2Chemical Names and Formulas
- Every substance is either an element or a compound
3Chemical Names and Formulas
- In nature, only the noble gas elements tend to
exist as isolated atoms - Noble gases are monatomic consisting of single
atoms
4Chemical Names and Formulas
- A compound consists of more than one kind of atom
- A compound is either molecular or ionic in nature
5Molecules and Molecular Compounds
- A molecule is the smallest electrically neutral
unit of a substance that still has the properties
of the substance
6Molecules and Molecular Compounds
- Molecules are made up of 2 or more atoms that act
as a unit - Diatomic molecules are composed of 2 atoms (O2)
- Triatomic molecules are composed of 3 atoms (O3
ozone)
7Molecules and Molecular Compounds
- Atoms of different elements combine chemically to
form compounds - Compounds composed of molecules are called
molecular compounds
8Molecules and Molecular Compounds
- Molecular compounds tend to have relatively low
melting and boiling points
9Molecules and Molecular Compounds
- Most molecular compounds are composed of 2 or
more nonmetals - The molecules of a given molecular compound are
all the same
10Ions and Ionic Compounds
- Not all compounds are molecular. Many compounds
are composed of particles called ions - Ions are atoms or groups of atoms that have a
positive or negative charge
11Ions and Ionic Compounds
12Ions and Ionic Compounds
- Metals tend to form ions by losing one or more
electrons - A cation is any atom or group of atoms that has a
positive charge
13Ions and Ionic Compounds
- For metallic elements, the name of a cation is
the same as the name of the element
Monatomic cation name of the element Ca2
calcium ion
14Ions and Ionic Compounds
- A metallic atom is chemically different than a
metallic ion
Na atom is highly reactive
15Ions and Ionic Compounds
- Nonmetals tend to form anions by gaining one or
more electrons
16Ions and Ionic Compounds
- An anion is an atom or group of atoms that have a
negative charge
17Ions and Ionic Compounds
- The name of an anion of a nonmetal is NOT the
same as the element name. - The name typically ends in ide
- Sulfur Sulfide
18Ions and Ionic Compounds
- Compounds composed of cations and anions are
called ionic compounds
19Ions and Ionic Compounds
- Although they are composed of ions, ionic
compounds are electrically neutral - The TOTAL positive charge the TOTAL negative
charge
20Ions and Ionic Compounds
- Ionic compounds are usually solid crystals at
room temperature, and melt at high temperatures
21Chemical Formulas
- A chemical formula shows the kinds and numbers of
atoms in the smallest representative unit of the
substance
22Chemical Formulas
- If the molecule has more than one atom of the
element, a subscript is used - Cl2
- subscript
23Molecular Formulas
- The chemical formula of a molecular compound is
called a molecular formula - CO2
24Molecular Formulas
- Molecular formulas show the composition of a
molecule, NOT the structure
25Formula Units
- Chemical formulas can also be written for ionic
compounds - Formula units are used to represent an ionic
compound. - A formula unit is the lowest whole-number ration
of ions in the compound
26Formula Units
- Ionic charges are used in the criss-cross method
to derive the correct formula, but they are not
shown in the formula - Mg2 Cl-1
- MgCl2
27Monatomic Ions
- For monatomic ions, the ionic charges can be
determine by using the periodic table
28Predicting Ionic Charges
Group 1
Lose 1 electron to form 1 ions
H
Li
Na
K
29Predicting Ionic Charges
Group 2
Loses 2 electrons to form 2 ions
Be2
Mg2
Ca2
Ba2
Sr2
30Predicting Ionic Charges
Group 13
Loses 3 electrons to form 3 ions
B3
Al3
Ga3
31Monatomic Ions
- Metallic elements tend to LOSE electrons. Metals
in group IA, 2A, and 3A lose electrons when they
form cations
32Monatomic Ions
- The ionic charge is positive and is NUMERICALLY
equal to the group number
33Predicting Ionic Charges
Group 14
Lose 4 electrons or gain 4
electrons?
Neither! Group 13 elements rarely form ions.
34Predicting Ionic Charges
Nitride
N3-
Group 15
Gains 3 electrons to form 3- ions
P3-
Phosphide
As3-
Arsenide
35Predicting Ionic Charges
Oxide
O2-
Group 16
Gains 2 electrons to form 2- ions
S2-
Sulfide
Se2-
Selenide
36Predicting Ionic Charges
F1-
Br1-
Fluoride
Bromide
Group 17
Gains 1 electron to form 1- ions
Cl1-
Chloride
I1-
Iodide
37Monatomic Ions
- The numerical charge of an ion of a Group A
nonmetal is determined by subtracting the group
number from 8 - Nonmetals tend to gain electrons and form anions,
so the sign of the charge is negative
38Predicting Ionic Charges
Group 18
Stable Noble gases do not form ions!
39Monatomic Ions
- Noble gases do not form ions
40Predicting Ionic Charges
Groups 3 - 12
Many transition elements
have more than one possible oxidation state.
Iron(II) Fe2
Iron(III) Fe3
41Predicting Ionic Charges
Groups 3 - 12
Some transition elements
have only one possible oxidation state.
Zinc Zn2
Silver Ag
42Monatomic Ions
- Many transitional metals are capable of forming 2
cations. There are 2 ways to name them. The
stock name uses a Roman numeral (I, II, III) in
parentheses after the symbol indicating the
charge.
43Monatomic Ions
- The classical naming system uses a root word with
different suffixes - The suffix ous is used to name the cation with
the lower of the 2 ionic charges - Fe2 is ferrous ion
- The suffix ic is used with the higher of the 2
ionic charges - Fe3 is ferric ion
44Polyatomic Ions
- Polyatomic ions are tightly bound groups of atoms
that behave as a unit and carry a charge
45Polyatomic Ions
- MOST polyatomic ions end in ite or-ate. 3
exceptions ammonium ion (NH4), cyanide ion
(CN-) and hydroxide ion (OH-) - The charge of each polyatomic ion in a given pair
is the same, but the ite ending indicates one
less oxygen atom than the ate ending - NO3- nitrate NO2- nitrite
- SO42- sulfate SO32- sulfite
46Writing Formulas for Binary Ionic Compounds
- Compounds composed of 2 elements are called
binary compounds - H2O
- When writing the formula for a binary compound,
the cation is ALWAYS written first
47Writing Formulas for Binary Ionic Compounds
- The positive charge the negative charge. The
net ionic charge must 0. - Written using the criss-cross method, but
remember to use the LOWEST whole number ratio of
ions. Ca2 and S2- would criss-cross to Ca2S2,
but the lowest whole number ratio of ions reduces
to CaS
48Naming Binary Ionic Compounds
- Name the compound by naming the ions in the order
written in the formula - Na and Br- NaBr
- sodium bromide sodium bromide
- ion ion
49Naming Binary Ionic Compounds
- The name of the transition metal that has more
than one ionic charge must include a Roman
numeral (or the proper suffix) - Fe2 and Cl- FeCl2
- iron (II) chloride iron (II) chloride
- ion ion
- Ferrous chloride ferrous chloride
- ion ion
50Ternary Ionic Compounds
- Ternary compounds contain 3 elements
- CaCO3 calcium carbonate
- 1 2 3
51Ternary Ionic Compounds
- Write the formula for each ion in the order
listed in the name (cation followed by anion),
then use the criss-cross method to determine the
subscripts. If more than 1 polyatomic ion is
needed, place the polyatomic ion formula in
parentheses, followed by a subscript showing the
number needed - Mg2 and OH- Mg(OH)2
- magnesium hydroxide magnesium
- ion ion hydroxide
- When naming ternary ionic compounds from their
formulas, you must recognize the polyatomic ions
first
52Binary Molecular Compounds
- Binary molecular compounds are composed of 2
nonmetals - They are composed of molecules, NOT IONS, so the
criss-cross method will NOT work - Use prefixes to tell how many atoms are present
53Binary Molecular Compounds
Prefix Mono- Di- Tri- Tetra- Penta-
Number 1 2 3 4 5
Prefix Hexa- Hepta- Octa- Nona- Deca-
Number 6 7 8 9 10
54Binary Molecular Compounds
- Always end the name in ide
- The vowel at the end of a prefix is often dropped
when the name of the element begins with a vowel
(carbon monoxide not monooxide) - When a single atom of the FIRST element, omit the
prefix mono-
55Binary Molecular Compounds
- CO2
- 1st element one carbon, 2nd element, two
oxygens - Drop the mono and name di, oxygen changes
ending - to oxide
- Carbon dioxide
56Naming Common Acids
- Consider acids to be combinations of anions
connected to as many hydrogen ions (H) as needed
to make the molecule electrically neutral - If the acid is a binary compound
- hydro - root name of anion -ic acid
- H2S hydro sulfur ic acid hydrosulfuric
acid
57Naming Common Acids
- If the acid contains a polyatomic anion, omit the
hydro -, and change an ate suffix to ic acid,
or change an ite suffix to ous acid - H2SO4 sulfuric acid
- H2SO3 sulfurous acid