Transcript NAMING AND WRITING CHEMICAL COMPOUNDS

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Ions of some
transition elements
can have more than
one possible charge.
Such elements are
called MULTIVALENT
species.
For example, what are
the 2 possible charges
for copper – Cu?
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WE use ROMAN
NUMERALS to indicate
the type of charge on
these multivalent ions.
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1+
2+
3+
4+
5+
6+
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I
II
III
IV
V
VI
ONLY USE WITH
MULTIVALENT IONS!
RULES
1. Use ROMAN NUMERALS to determine the
ION CHARGE of the MULTIVALENT ION.
2. If ROMAN NUMERAL are NOT given, use
the charge found on the top in each box
on the table.
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EXAMPLE:
copper (II) oxide
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lead (IV) sulfide
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tin sulfide
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Do the sheet on the following page!
Remember to ONLY use the ROMAN
NUMERAL with the MULTIVALENT IONS!!!
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RULES
1. Write the names of the ions.
2. Write the ROMAN NUMERAL for the
MULTIVALENT ION. There are 2 METHODS:
1. METHOD 1
Charges must add up to zero.
1. METHOD 2
Charge of Anion X Subscript of Anion
Subscript of Cation
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PbI2
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Fe2O3
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CuCl
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MnO2
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Do the next 2 sheets for homework!
Remember, doing some workings can help
prevent any mistakes!!!
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DEFINITION:
◦ Polyatomic ions
are GROUPS OF
ATOMS acting as
1 ION, carrying an
OVERALL CHARGE.
On the back of your
periodic table, there is a
POLYATOMIC ION TABLE.
Endings of polyatomic
ions are easily
recognizable as they are
often –ATE or –ITE,
providing a good clue.
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EXAMPLES:
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nitrate
nitrite
cyanide
hydroxide
bicarbonate
chlorate
carbonate
sulfate
phosphate
ammonium
acetate
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lithium sulfate
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ammonium carbonate
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hydrogen dichromate
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sodium acetate
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HNO3
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NaOH
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KMnO4
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Cu2SO4
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hydrogen carbonate is AKA bicarbonate HCO3-
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hydrogen sulfate is AKA bisulfate HSO4-
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tetraborate B4O72-
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silicate SiO32-
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glutamate C5NH8O4-
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Do the next 2 Sheets for homework!!!
Remember to use the crossover method for
charges.
You may find it helpful to use BRACKETS
around ALL polyatomic ions when writing the
formulae.
1.
Simple Ions
Names
Formulas
- write the name of the positive ion
- determine the charge on each ion
- write the name of the negative ion
followed by -ide
- cross over the charges to write the formula
eg.
eg.
NaCl
sodium chloride
Mg3N2
magnesium nitride
calcium phosphide
Ca 2+
P3 Ca3P2
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Polyatomic Ions
Names
Formulas
- write the name of the positive ion
- determine the charge on each ion
- write the name of the negative ion
eg.
CaSO4 calcium sulfate
Al(OH)3
- cross over the charges to write the formula
eg.
magnesium nitrate
aluminum hydroxide
Mg2+
NO3Mg(NO3)2
3.
MultiValent Metals
- use Roman Numerals to indicate the ion charge(Stock System)
OR
- use the suffix -ic to indicate the smaller ion charge or -ous for the larger ion charge.
Names
eg.
Formulas
CoCl2 - cobalt(II) chloride
- cobaltous chloride
eg.
nickel(II) nitride
Ni2 +
N3-
(cross over)
CoCl3 - cobalt(III) chloride
- cobaltic chloride
NOTE:
Ni3N2
After crossing over the charges to get the formula, make sure you are using the
simp lest ratio between the ions.
eg. magnesium oxide - Mg2 O2 becomes MgO
DON’T USE PREFIXES FOR IONIC COMPOUNDS.
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Hydrated ionic compounds have WATER
attached to their crystal lattice structure.
Solutions become hydrated when they are
crystallized from a water solution.
They are often recognizable by eye because
they are often SHINY and TRANSLUCENT.
Examples:
◦ Bluestone, Epsom salts, Rock salts
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BLUESTONE  CuSO4 ∙5H2O
◦ 5 H2O molecules attached to each CuSO4 compound.
◦ The “dot” represents a weak bond.
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We indicate the presence of water with the
word HYDRATE and we indicate the number of
water molecules with our GREEK PREFIXES:
MONO 1, DI 2, TRI 3, TETRA 4, PENTA 5, HEXA
6, HEPTA 7, OCTA 8, NONA 9, DECA 10
ANHYDROUS: NO water attached
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barium chloride dihydrate
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potassium hydroxide hexahydrate
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sodium carbonate octahydrate
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cobalt (II) chloride decahydrate
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CaSO4 ∙2H2O
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Na3PO4 ∙4H2O
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HCN ∙ 3H2O
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HOMEWORK:
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◦ DO THE SHEET ON HYDRATED IONIC COMPOUNDS
ON THE NEXT PAGE OF YOUR HANDOUT.