Formula Writing and Nomenclature

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Formula Writing and Nomenclature
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What is an ion?

• An ion is a ______________.
• It may be a ____ or ___charge.
• Lose electrons ? cation ()
• Gain electrons ? anion (-)

charged particle.

-
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Why do atoms gain or lose electrons?

• To become more ______.
• Electrons come from ___________.
• One ion ______ e- and the other _____e- to form a
  _____.

stable
other atoms
loses
gains
bond
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Do ions follow rules? YES!

• Octet Rule _____________
• Tendency of valence electrons to rearrange to
  form a ________________ .
• THE MAGIC NUMBER________?

• The Rule of 8

stable/full valence shell
Happy Ion
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Examples
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• Na 2-8
• F 2-7

-1
8
-1
Opposites attract!? NaF
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Do ions follow rules? YES!

• Duet Rule___________
• For atoms so small their valence shell is the
  ______ energy level which can only hold
  ___________.

The Rule of 2
first
two electrons
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Examples

• H can gain ___ e- to form _____.
• H can lose ____ e- to form_____.
• Li loses _____ e- to form _____.
• Be loses ____ e- to form _____.
• B loses _____ e- to form _____.

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H-1
1
H1
1
Li1
2
Be2
3
B3
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Writing Formulas

• All compounds have a charge of zero.
• When writing formulas, all ions have to add up to
  zero.

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IUPAC

• IUPAC- International Union of Pure and Applied
  Chemists (created this naming system)

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Forming Binary Ionic Compounds

• Binary two elements
• Ionic one metal and one nonmetal
• Transfer of electrons
• Not called molecules!

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Writing Binary Ionics

• Write each ion (metal first)
• Crisscross the charges
• Drop the and
• Write numbers as subscripts

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Binary Ionic Compounds

• Example
• magnesium chloride

Mg2
Cl-1
MgCl2
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Why does this work?
MgCl2 means
Cl-1
Mg2
Cl-1
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Binary Ionic Compounds

• Example
• barium oxide

Ba2
O-2
BaO
Ba2O2
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Practice

• Sodium bromide
• Calcium fluoride
• Magnesium oxide
• Lithium oxide
• Aluminum oxide
• Magnesium fluoride
• Potassium iodide
• Aluminum sulfide

NaBr
CaF2
MgO
Li2O
Al2O3
MgF2
KI
Al2S3
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Forming Ternary Ionics

• Contain 3 or more elements
• Combination of a metal and a polyatomic ion
  (Table E)

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Writing Ternary Ionics

• Write each ion (positive first)
• Crisscross the charges
• Drop the and
• Write numbers as subscripts
• Keep polyatomic ions in parentheses if more than
  1
• Never change a polyatomic ion!!!!!

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Ternary Ionic Compounds

• Example
• ammonium chloride

NH41
Cl-1
NH4Cl
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Ternary Ionic Compounds

• Example
• lithium carbonate

Li1
CO3-2
Li2CO3
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Ternary Ionic Compounds

• Example
• calcium hydroxide

Ca2
OH-1
Ca(OH)2
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Why does this work?
Ca(OH)2 means
OH-1
Ca2
OH-1
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Practice

• Magnesium hydroxide
• Potassium sulfate
• Sodium phosphate
• Calcium nitrate

Mg(OH)2
K2SO4
Na3PO4
Ca(NO3)2
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Stock System for Ionics

• Some metals can have more than one oxidation
  state (i.e. transition metals)
• Use roman numerals
• Examples

Copper (I) chloride
Cu1
Cl-1
CuCl
Copper (II) chloride
CuCl2
Cu2
Cl-1
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Practice

• Mercury (II) oxide
• Vanadium (V) bromide
• Copper (I) oxide
• Tin (IV) bromide

HgO
VBr5
Cu2O
SnBr4
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Forming Molecular Compounds

• Composed of two non-metals
• Electrons are shared so no ions are formed
  (covalent bonding).
• Called molecules
• Prefix system- tells you how many atoms of each
  element

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Prefixes
prefix meaning
Mono- 1
Di- 2
Tri- 3
Tetra- 4
Penta- 5
Hexa- 6
Hepta- 7
Octa- 8
Nona- 9
Deca- 10
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Molecular Compounds

• Examples
• Carbon monoxide
• Carbon dioxide
• Phosphorous trichloride
• Phosphorous pentachloride
• Carbon tetrachloride

CO
CO2
PCl3
PCl5
CCl4
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Practice

• Phosphorous trichloride
• Dichlorine monoxide
• Sulfur tetrafluoride
• Dinitrogen trioxide
• Iodine monochloride

PCl3
Cl2O
SF4
N2O3
ICl
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Naming Ionic Compounds
Ionic Compounds (formula units)- Metal and
non-metal
Write cation name first (use roman numerals if
more than one oxidation state).
1.
Write the first syllable of the anion and add
ide. OR just name the polyatomic ion.
2.
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Examples Ionics

• LiBr
• Na2SO4
• CuCl2

lithium bromide
sodium sulfate
copper (II) chloride
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Naming Molecular Cmpds
Molecular Compounds (molecules)- two non-metals
Use prefix system on first element (except Mono).
1.
Use prefix system on the second element
(including mono) and add ide ending.
2.
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Examples Molecular

• N2O5
• CO
• PCl3

Dinitrogen pentoxide
Carbon monoxide
Phosporous trichloride
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Empirical Formulas vs. Molecular Formulas

• Compounds exist with a definite ratio of atoms
  (ex water has 2 H per 1 O)
• Empirical formula lowest whole number ratio
• Molecular formula actual formula (can be
  empirical also).

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Examples

• C2H8 is a molecular formula (can be reduced).
• CH4 is an empirical formula (cant be reduced).