Chemical Names

1
Chapter 9

• Chemical Names
• Formulas

2
Ionic vs. Covalent

• Ionic bonds form between a metal cation and a
  non-metal anion.
• There is a full transfer of electrons.
• A covalent (molecular) bond occurs between two
  non-metals.
• Electrons are shared.

3
IONS

• Ion an atom or group of atoms with a charge
• Cation Ion with a positive charge
• Anion Ion with a negative charge
• Monatomic ion consist of a single atom
• Polyatomic ion consists of more than one type
  of atom

4
CATIONS

• Elements in group 1, 2, and 3 lose electrons and
  form cations.
• Why is sodium 1 and magnesium is 2?
• (hint drawing a diagram may help)
• Atoms try to achieve noble gas configuration with
  their electrons.
• Cations have the same name as the element from
  which they form

5
ANIONS

• Elements in group 15, 16, 17 gain electrons to
  form anions
• How many electrons will chlorine gain?
• what will its charge be?
• Monatomic anions have the ending -ide
• The remaining elements in group 4 14 dont
  normally form ions. Why?

6
Ions of Transition Metals

• Transition metal cations may have more than one
  possible charge.
• Iron for example can have a 2 or a 3 oxidation
  state.
• A roman numeral in parantheses shows the
  oxidation state of the metal.
• e.g. Iron (III), Iron (II)

7
continued

• A few transition metals have only one oxidation
  state (Ag, Cd2, Zn2) and do not need a Roman
  Numeral.
• Can you find any other transition metals that
  have only one oxidation state?

8
Writing Formulas

• Formulas need to have an overall charge of zero.
• Write the symbol of the cation first then the
  anion. Then, add whatever subscripts are needed
  to balance the charges.
• Example
• Potassium chloride is composed of
• K and Cl -
• The formula is KCl

9
CONTINUED

• The formula for lithium oxide is Li2O
• Each lithium has one positive charge, so two
  lithium atoms are needed to balance the 2 charge
  on oxygen.
• The formula for aluminum oxide is Al2O3
• How do we come up with this formula?

10
The Crisscross Method

• If the charges do not already add to zero,
  the numerical value of the charge can be crossed
  down to become the subscript of the other ion.
• Al3 O2-

11
Polyatomic Atoms

• Composed of more than one atom, most of these
  ions end in ite or -ate

12
Formulas With Polyatomics

• Write the symbols for the cation followed by the
  formula for the polyatomic anion, and balance the
  charges.
• If you need more than one polyatomic ion,
  (parentheses are necessary)
• Calcium nitrate is written Ca(NO3) 2

13
PRACTICE

• Write the correct formula for the following
• Lithium fluoride
• Magnesium chloride
• Aluminum sulfide
• Calcium phosphate
• Potassium chlorite

14
Things to keep in mind

• There are three common polyatomic ions that end
  in ide
• Hydroxide
• Peroxide
• Cyanide
• You may run into 3 names together, e.g. sodium
  hydrogen carbonate.

15
Naming Molecular Compounds

• Molecular compounds are covalently bonded and are
  composed of two non-metals.
• What are the names for CO2 and CO?
• Carbon dioxide carbon monoxide.
• Where do we find each of these gases?

16
PREFIXES

• Prefixes tell us how many atoms of an element are
  present in each molecule of a compound.

• Omit the prefix mono- when the formula
  contains only one atom of the first element in
  the name.
• The ending of the second element is ide
• The vowel at the end of a prefix is dropped if
  the name of the elements begins with a vowel.

17
Writing Formulas for Molecular Compounds

• The prefix tells you the subscript of each
  element in the formula.
• Silicon carbide has no prefixes and has the
  formula SiC.
• Dinitrogen tetroxide is N204

18
ACID

• An acid contains one or more hydrogen atoms and
  produces H ions when dissolved in water.
• Formic Acid Hydrofluoric
  Acid

19
Naming Acids

• Formulas are generally in the form HnX, where X
  is an anion.
• The name system depends on the name of the anion,
  suffix.

20
RULES

• When the anion ends in ide, the acid name begins
  with hydro and ends in ic (followed by the
  word acid)
  ex. HCl hydrochloric
  acid
• 
  
• When the anion ends in ite, the acid name ends
  in ous (followed by the word acid)
  ex.
  H2S03 sulfurous acid.
• 3) When the anion ends in ate, the acid
  name ends in ic (followed by the word acid)
  
  ex. HN03 nitric acid.

21
Naming Bases

• Bases are named the same way as other ionic
  compounds.
• Ex. NaOH sodium hydroxide
• Al(OH)3 aluminum hydroxide