Nomenclature

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Nomenclature Formula Writing Review
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Why do elements bond together?

• Elements react with each other so that they may
  have a full outer shell of electrons.
• They will share or steal electrons from each
  other in order to achieve this.
• Noble gasses already have full outer shell, and
  this is why they do not tend to react with other
  elements!

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Simple Chemical Formulae

• Each element has a combining capacity which
  explains how many available bonding spaces it
  has.
• This is linked to the number of valence (outer
  orbital) electrons the element has.
• When 2 elements combine, every bonding space must
  be used.

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The criss-cross method

• Example lithium and oxygen
• What are the combining capacities?
• Lithium 1
• Oxygen 2

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Because the 1 is implied, we simply write the
formula as Li2O.
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• When possible, the formula must be reduced by its
  lowest common denominator.
• Example magnesium and oxygen

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Try these!

1. Sodium and bromine
2. Boron and oxygen
3. Calcium and iodine
4. Magnesium and sulphur

• NaBr
• B2O3
• CaI2
• MgS

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Nomenclature(naming of molecules)

• You should be familiar with four basic naming
  rules from your previous years.

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A. Metal-Nonmetal

• Write the name of the metal first
• The name of the nonmetal is written second, with
  the ending of the name changed to ide
• Example Li2O
• Lithium oxide

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B. Nonmetal-Nonmetal

• Write the names of the nonmetals in the order
  that you find them (left to right) on the
  periodic table.
• Change the ending of the last one to ide
• Use prefixes to indicate how many of each element
  is present
• The nonmetals are rebels! They do not always
  follow the criss-cross rule you just reviewed.
  Fortunately, you can determine the formula from
  the name.

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1. Mono- generally not used for the first
   element
2. Di-
3. Tri-
4. Tetra-
5. Penta-
6. Hexa-
7. Hepta-
8. Octa-
9. Nona-
10. Deca-

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• Example P5Cl2
• Pentaphosphorous dichloride

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Your turn

1. CO
2. Si4O2
3. NI3

• Carbon monoxide
• Tetrasilicon dioxide
• Nitrogen triiodide

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C. Multivalent metals

• These metals are found in the transition elements
  area (middle of the periodic table)
• Some transition metals have more than one
  possible combining capacity. For example, copper
  can have a combining capacity of either 2 or 1.
• Roman numerals are used in the name to indicate
  which ion is being used.

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• Example
• copper (I) chloride copper (II) chloride

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• You need to reverse this process to convert
  from the formula to the name!
• This is nickel (II) nitride.

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Your turn again!

1. Cobalt (II) selenide
2. Tin (IV) bromide
3. NiS
4. Fe2O3

• CoS
• SnBr4
• Nickel (II) sulphide
• Iron (III) oxide

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D. Polyatomic Ions

• Your beloved data table contains a list of common
  ions and their charges.
• For naming and formula purposes, treat the ions
  as a single unit, and follow the criss-cross rule
  as you have already been doing.

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• Hints
• You will be able to recognize polyatomic names
  because they are the only ones which do not end
  in IDE!!
• You will be able to recognize polyatomic formulae
  because they are the only ones with three or more
  elements.
• (Of course, this will change as the year goes
  on.) ?

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• Example Calcium permanganate

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Final round for you to try!!!

• Sodium phosphate
• Strontium chlorate
• NH4Cl
• CaC2O4

• Na3PO4
• Sr(ClO3)2
• Ammonium chloride
• Calcium oxalate

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