Transcript Honors Chapter 6 - Barnegat Township School District

Honors Chapter 9 (and some
Chapter 7)
Chemical Names and
Formulas
Chemical formula - combination of
symbols that represent the composition
of a compound
• Shows elements present and number of
atoms
subscripts
• Represent the number of atoms of that
element in the compound
• No subscript is an “understood” 1
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NaCl
1 Na 1 Cl
H2SO4
2H 1S 4O
Ca(ClO3)2 ?????
1 Ca 2 Cl
6O
Ionic – transfer of electrons
Called a “formula unit”
Covalent – share electrons called “molecule”
IONIC COMPOUNDS
Four different types we will learn
about
Metal + nonmetal (binary ionic)
Metal + polyatomic ion
Polyatomic ion + polyatomic
ion
Polyatomic ion + nonmetal
Monatomic ions – ions consisting of only
one atom
 Charges can often be determined by
using the periodic table
 Metallic elements – tend to lose
electrons to form cations
 Group 1 all 1+
 Group 2 all 2+
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 Nonmetals
tend to gain
electrons when they bond
with metals – form anions
 Many
have more than one
common ionic charge
Are going to use roman numerals
Oxidation number
• Indication of how many electrons it will
gain or lose when it forms a bond
• Gains or loses electrons – forms an ion
• Charged particle
• Can be found for each element on the
periodic table
• Refer to yours!!!
• Some elements have more
than 1 oxidation number –
that means they can form
more than one type of
compound
 When
a single atom takes on a
charge (by gaining or losing
electrons) – it forms a
“monatomic ion”
 Ion made up of more than 1 atom
– “polyatomic” ion
Monatomic ions
 Na+ Ca+2
Cl-
O-2
Polyatomic ions
 CO3-2
ClO3-
OH-
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Why would an atom want to form an ion?
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Remember the “octet rule”
Wants a filled outer shell
 For most atoms, that is 8
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Samples on board using electron dot
notation
 Na and Cl
 Ca and Cl
 Al and Cl
 Ca and S
 K and N
you do
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1) Metal + nonmetal
Metal always written first – has
positive oxidation number
(written first)
Nonmetal written second – has
negative oxidation number
Can use “criss-cross”
method to arrive at correct
formula.
Must remember to simplify
subscripts if possible!!
Magnesium oxide - MgO
Naming binary ionic compounds
Metal full name first
Nonmetal name with “ide” ending
NaCl
sodium chloride
CaCl2
calcium chloride
LiF
lithium fluoride
AlBr3
aluminum bromide
Some metals have multiple
oxidation numbers
Use Roman numerals to specify the
oxidation number used
I, II, III, IV, V, VI, VII, VIII
Transition metals characteristically
have multiple oxidation numbers
ONLY USE ROMAN NUMERALS IF
THE METAL HAS MORE THAN
ONE OXIDATION NUMBER LISTED
Nonmetals may have more
than one oxidation number,
you just use the first
number listed - NEGATIVE
Examples:
Co, Ni, Cu, Fe, Mn
Always check before writing name
for the compound
FeCl2
Iron(II) chloride
FeO
Fe2O3
Write formulas for the following
calcium sulfide
strontium bromide
chromium(III) chloride
iron(II) oxide
CaS
SrBr2
CrCl3
FeO
Name the following compounds
Fe2O3
KI
CuO
NiCl3
CrO3
Iron(III) oxide
Potassium iodide
Copper(II) oxide
Nickel(III) chloride
Chromium(VI) oxide
2. Metal + polyatomic ion
 Almost
all polyatomic ions have
a negative charge
 2 you are responsible for have a
positive charge NH4+ and H3O+
 Polyatomic ions travel as a unit
 Page 257 list of polyatomic ions
NEVER
CHANGE THE
SUBSCRIPTS IN A
POLYATOMIC ION
THAT MEANS
NEVER!!!!!!!
Can use same “criss-cross” method for
determining the correct formula
 Same rules apply – must factor the
subscripts if you can (only the oxidation
numbers that are used – NOT THE
SUBSCRIPTS OF THE POLYATOMIC
ION!!!!!!
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At first, always put a parenthesis around
the polyatomic ion
 Only time the parenthesis can be
dropped is if a “1” criss-crosses down or
if the subscript factors to a “1”
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Don’t forget to include a roman numeral
in the name if the metal has multiple
oxidation numbers!!!!!!
Examples on board
Naming
Metal name first (only use
roman numeral if the metal has
more than one oxidation
number!!!)
Second is the name of the
polyatomic ion – taken directly
from the table!!
Don’t make
up your own
name!!!!!!!!
Characteristics of Ionic Compounds
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Representative unit = “formula unit”
Type of elements: Metal with nonmetal
Physical state: crystalline solid (hard)
High melting point
Most are soluble in H2O
• Poor conductors of electricity in the
solid state
–But good conductors when
melted (molten) or dissolved in
H2O (aq) (ions free to move)
Molecular Compounds (covalent)
• Representative unit – “molecule”
(bonded covalently)
• Type of elements – nonmetals
• Physical state – solid, liquid, gas
– Solids – low melting point, brittle
• Molecule – electrically neutral
group of atoms that act as a unit
Naming binary molecular compounds
• 2 elements in the compound
– Both nonmetals!
• 2 naming systems
– Prefix system
– Stock system (roman numerals)
• Both systems are correct
• I’m sure you will prefer the prefix
system!
Prefixes you must memorize!
Number of
atoms
1
2
3
4
5
6
7
8
9
10
Prefix used
mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deca
• When 2 nonmetallic elements combine
– Often do so in more than one way
– Example
CO
CO2
• Problem with calling them both
“carbon oxide”
• CO2 – you exhale. It is normally present in the
air you breathe
• CO – hopefully is not in the air you breathe
• In large amount R.I.P.
• Catalytic converter – cars
– Converts CO to CO2
Naming binary molecular compounds
• Prefix + first element name
• Followed by prefix + 2nd element name with
“ide” ending
• ******only time you can neglect a
prefix is if the first element in the
compound is a single atom
• PCl3
phosphorus trichloride
• CO
• Carbon monoxide (not monocarbon monoxide!)
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Don’t use “double vowels”
Change if a “tongue twister”
Monooxide  monoxide
Decaoxide  decoxide
• Trioxide – is fine
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N2O
Dinitrogen monoxide
SF6
Sulfur hexafluoride
N2H4
Dinitrogen tetrahydride
– NO FACTORING ALLOWED!!!
• P2O3
• Diphosphorus trioxide
Name the following:
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CS2
Cl2O7
N2O5
CCl4
CrCl3
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Carbon disulfide
Dichlorine heptoxide
Dinitrogen pentoxide
Carbon tetrachloride
Chromium III chloride GOTCHA!!!!!
Write formulas for the following:
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carbon tetrabromide
dinitrogen tetrahydride
boron trichloride
diphosphorus trioxide
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CBr4
N2H4
BCl3
P2O3
• A molecular compounds
worksheet just for you!!
Network covalent compounds
• Covalent compounds that are not made up of
individual molecules.
• All the atoms are joined in a covalently bonded
three dimensional network
• No distinct units in these compounds
• Have very high melting points
• SiC
SiO2 Si3N4
Acids you should know!
• Oxyacids – contain H, O and a third element
(usually a nonmetal)
• Acetic
HCH3COO (acetate ion)
• Nitric
HNO3
(nitrate ion)
• Nitrous
HNO2
(nitrite ion)
• Phosphoric H3PO4
(phosphate ion)
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Sulfuric
Sulfurous
Carbonic
Hypochlorous
Chlorous
Chloric
Perchloric
H2SO4
H2SO3
H2CO3
HClO
HClO2
HClO3
HClO4
(sulfate ion)
(sulfite ion)
(carbonate ion)
(hypochlorite ion)
(chlorite ion)
(chlorate ion)
(perchlorate ion)
 HF
 HCl
 HBr
 HI
hydrofluoric acid
hydrochloric acid
hydrobromic acid
hydroiodic acid