Chapter 9 Chemical Names and Formulas

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Chapter 9Chemical Names and Formulas
9.1 Naming Ions9.2 Naming and Writing Formulas
for Ionic Compounds9.3 Naming and Writing
Formulas for Molecular Compounds9.4 Naming and
Writing Formulas for Acids and Bases
Created by B. Shia 11-07
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9.1 Naming Ions

• Monatomic Ions
• How are the charges of Group A metal and
  nonmetal ions related to their positions in the
  periodic table?
• Monatomic ions consist of a single atom with a
  positive or negative charge resulting from the
  loss or gain of one or more valence electrons,
  respectively.

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Monatomic Ions
Cations When the metals in Groups 1A, 2A, and 3A
lose electrons, they form cations with positive
charges equal to their group number.The names
of the cations of the Group 1A, Group 2A, and
Group 3A metals are the same as the name of the
metal, followed by the word ion or cation.
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Monatomic Ions

• These elements have ionic charges that can be
  obtained from their group numbers

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Monatomic Ions
Anions The charge of any ion of a Group A
nonmetal is determined by subtracting 8 from the
group number. Anion names start with the stem of
the element name and end in -ide. These Group A
elements form anions.
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Monatomic Ions
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Monatomic Ions

• Ions of Transition Metals
• How are the charges of some transition metal
  ions determined?
• The charges of the cations of many transition
  metal ions must be determined from the number of
  electrons lost.

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Monatomic Ions
There are two methods are used to name the ions
of transition metals the Stock system and the
classical method In the Stock system, a Roman
numeral in parentheses is placed after the name
of the element to indicate the numerical value
of the charge. (Cu is copper (I) ion) In an
older less, useful method, the classical name of
the element is used to form the root name for the
element. (Cu is cuprous ion)
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Conceptual Problem 9.1
a) K, cation, potassium ion
b) I-, anion, iodide ion
c) S2-, anion, sulfide ion
d) Pb4, cation, lead (IV) ion
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Polyatomic Ions

• What are the two endings of the names of most
  polyatomic ions?
• Some ions, called polyatomic ions, are composed
  of more than one atom.
• The names of most polyatomic anions end in -ite
  or -ate.

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Polyatomic Ion
These models show the structures of four common
polyatomic ions.
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Polyatomic Ions

• Names and formulas of some common polyatomic ions

Know nitrate, hydroxide, sulfate, carbonate,
phosphate, ammonium possibly acetate
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9.1 Section Quiz

• 1. When metals from groups 1A, 2A, and 3A form
  cations, the charge on the ion is equal to
• 8 minus the group number.
• the group number minus 8.
• the period number.
• the group number.

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9.1 Section Quiz

• 2. Which of the following are positively charged
  polyatomic ions?
• (I) ammonium ion
• (II) perchlorate ion
• (III) ferric ion

a) I only b) II only c) III only d) I and III
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9.1 Section Quiz
3. If the name of an ion ends in -ite or -ate,
the ion is a
a) polyatomic cation. b) polyatomic anion. c)
transition metal cation. d) monatomic anion.
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9.2 Naming and Writing Formulas for Ionic
Compounds

• Binary Ionic Compounds
• How are the names of binary ionic compounds
  determined?
• A binary compound is composed of two elements and
  can be either ionic or molecular.
• To name any binary ionic compound, place the
  cation name first, followed by the anion name.
• How do you write the formulas for binary ionic
  compounds?
• Write the symbol of the cation and then the
  anion. Add whatever subscripts are needed to
  balance the charges.

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Conceptual Problem 9.2
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Conceptual Problem 9.2
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Conceptual Problem 9.2
a) NaI
c) K2S
b) SnCl2
d) CaI2
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Compounds With Polyatomic Ions
How do you write the formulas and names of
compounds containing polyatomic ions? Write the
symbol for the cation followed by the formula for
the polyatomic ion and balance the charges.
For example, calcium nitrate is composed of a
calcium cation (Ca2) and a polyatomic nitrate
anion (NO3). In calcium nitrate, two nitrate
anions, each with a 1 charge, are needed to
balance the 2 charge of each calcium cation. The
formula for calcium nitrate is Ca(NO3)2.
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Conceptual Problem 9.2
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Conceptual Problem 9.2
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Conceptual Problem 9.2
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Conceptual Problem 9.2
a) (NH4)2SO3
b) Ca3(PO4)2
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Compounds With Polyatomic Ions

• Naming Compounds with Polyatomic Ions
• To name a compound containing a polyatomic ion,
  state the cation first and then the anion, just
  as you did in naming binary ionic compounds.
• ex. (NH4)2SO3
• Ca3(PO4)2

ammonium sulfite
calcium phosphate
Dont change polyatomic ion names like you would
a monotomic anion!
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9.2 Section Quiz

• 1. The correct name for CrCl3 is
• a) chromium chlorine.
• b) chromium(III) chloride.
• c) monochromium trichloride.
• d) chromium(III) trichloride.

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9.2 Section Quiz

• 2. What is the correct formula for strontium
  nitride?
• a) Sr3N2
• b) SrN2
• c) Sr2N3
• d) Sr3N

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9.2 Section Quiz

• 3. Which one of the following compounds is named
  correctly?
• a) sodium chlorite, NaClO
• b) potassium nitrate, KNO2
• c) sodium acetate, NaC2H3O2
• d) lithium sulfate, Li2SO3

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9.3 Naming and Writing Formulas for Molecular
Compounds

• What does a prefix in the name of a binary
  molecular compound tell you about the compounds
  composition?

A prefix in the name of a binary molecular
compound tells how many atoms of an element are
present in each molecule of the compound.
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Naming Binary Molecular Compounds

• 9.3

• Carbon and oxygen combine to form carbon
  monoxide (CO) and carbon dioxide (CO2), but these
  two invisible gases are very different.

Sitting in a room with small amounts of CO2 in
the air would not present any problems. If the
same amount of CO were in the room, you could die
of asphyxiation. A naming system that
distinguishes between these two compounds is
needed.
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Writing Formulas for Binary Molecular Compounds

• How do you write the formula for a binary
  molecular compound?

Use the prefixes in the name to tell you the
subscript of each element in the formula. Then
write the correct symbols for the two elements
with the appropriate subscripts.
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Naming Binary Molecular Compounds

• 9.3

• Some guidelines for naming binary molecular
  compounds
• Name the elements in the order listed in the
  formula.
• Use prefixes to indicate the number of each kind
  of atom.
• Omit the prefix mono- when the formula contains
  only one atom of the first element in the name.
• The suffix of the name of the second element is
  -ide.

Ex. Silicon carbide is a hard material like
diamond. The name silicon carbide has no
prefixes, so the subscripts of silicon and carbon
must be one. Thus, the formula for silicon
carbide is SiC.
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9.3 Section Quiz

• 1. Which of the following compounds is named
  INCORRECTLY?
• a) CS2, carbon disulfide
• b) BCl3, boron trichloride
• c) IF7, iodine heptafluoride
• d) PCl5, phosphorus hexachloride

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9.3 Section Quiz

• 2. Which of the following molecular compounds is
  named INCORRECTLY?
• a) SbCl3, antimony trichloride
• b) C2O5, dicarbon pentoxide
• c) CF4, carbon tetrafluoride
• d) H3As, hydrogen arsenide

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9.3 Section Quiz

• 3. The correct formula for tetraphosphorus
  trisulfide is
• a) P3S4
• b) S3P4
• c) P4S3
• d) S4P3

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9.4 Naming and Writing Formulas for Acids and
Bases

• Three rules can help you name an acid with the
  general formula HnX.
• When the name of the anion (X) ends in -ide, the
  acid name begins with the prefix hydro-. The stem
  of the anion has the suffix -ic and is followed
  by the word acid.
• When the anion name ends in -ite, the acid name
  is the stem of the anion with the suffix -ous,
  followed by the word acid.
• When the anion name ends in -ate, the acid name
  is the stem of the anion with the suffix -ic
  followed by the word acid.

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An acid is a compound that contains one or more
hydrogen atoms and produces hydrogen ions (H)
when dissolved in water. Acids have various uses.
Summary of Naming Acids
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• How are the formulas of acids determined?

• Use the rules for writing the names of acids in
  reverse to write the formulas for acids.
• What is the formula for hydrobromic acid?
  Following Rule 1, hydrobromic acid (hydro- prefix
  and -ic suffix) must be a combination of hydrogen
  ion (H) and bromide ion (Br). The formula of
  hydrobromic acid is HBr.

Know these acids (except carbonic) and the other
hydro- examples
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How are bases named? Bases are named in the same
way as other ionic compoundsthe name of the
cation is followed by the name of the anion. For
example, aluminum hydroxide consists of the
aluminum cation (Al3) and the hydroxide anion
(OH). The formula for aluminum hydroxide is
Al(OH)3. Be able to name bases.
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9.4 Section Quiz

• 1. The name for H2S(aq) is
• a) sulfuric acid.
• b) hydrosulfuric acid.
• c) sulfurous acid.
• d) hydrosulfurous acid.

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9.4 Section Quiz

• 2. The correct chemical name for NH4OH is
• a) nitrogen tetrahydrogen hydroxide.
• b) nitrogen pentahydrogen oxide.
• c) ammonium oxyhydride.
• d) ammonium hydroxide.