Transcript The Crazy “L” “Г” “٦”

The Crazy “L” “Г” “٦”
Polyatomic Ions
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Polyatomic ions normally (but not always)
consist of atoms that will share an
electrical charge.
Because of its electronegativity, the
oxygen is always negative, causing the
other nonmetal to be the positive part of
the ion.
Polyatomic Ions
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These ions exist in series or families of
related formulas such as: an ion family:
ClO4-1
Per__ate
ClO3-1
(parent ion)
__ate
ClO2-1
__ite
ClO-1
Hypo___ite
Polyatomic Ions
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Each member of the series/family has an
identical electrical charge, but a different
number of oxygen atoms.
For naming purposes, one ion is
designated as the parent ion.
All parent ions end with the suffix –ate.
Polyatomic Ions
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To name the other members of the family, we
may change the suffix (to –ite) and/or add a
prefix (either per- or hypo-)
 -ite: means to subtract one oxygen from
parent
 Per-: means to add one oxygen to the parent
(requires an –ate ending)
 Hypo-: means that two oxygens have been
subtracted from the parent (requires an –ite
ending)
Polyatomic Ions
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Example of an ion family:
 ClO4-1
 ClO3-1
Perchlorate
chlorate
 ClO2-1
chlorite
 ClO-1
hypochlorite
Polyatomic Ions
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The best strategy to naming and writing
the formulas for polyatomic anions is to
learn their parent ions.
Many of these (but not all) may be
predicted from the periodic table.
Polyatomic Ions
IIA
IVA
VA
VIA
VIIA
VIIA
BO3-3
CO3-2
NO3-1
n/a
n/a
Ne
SiO4-4
PO4-3
SO4-2
ClO3-1
Ar
AsO4-3
SeO4-2
BrO3-1
Kr
TeO4-2
IO3-1
Xe
AtO3-1
Rn
Polyatomic Ions
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Note the pattern:
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In the shaded area, all the parent ions have
three oxygens; in the non-shaded area, all
parent ions have four oxygens.
Except for IVA, all ions in the vertical columns
have the same charge.
Anion charges decrease as you approach the
noble gases.
Polyatomic Ions
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Unfortunately, no matter how hard we try,
it is impossible to predict the formulas and
charges of all ions. There are some
cations and anions that you simply have to
memorize.
Chemical Names and Formulas
Cations of the representative elements
IA
IIA
IIIA
IVA
VA
H+1
VIA
VIIA
VIIIA
He
Li+1
Be+2
B+3
C+4
Ne
Na+1
Mg+2
Al+3
Si+4
Ar
K+1
Ca+2
Ga+3
Ge+4
As+5
As+3
Kr
Rb+1
Sr+2
In+3
Sn+4
Sn+2
Sb+5
Sb+3
Xe
Cs+1
Ba+2
Ti+3
Ti+1
Pb+4
Pb+2
Bi+5
Bi+3
Rn
Fr+1
Ra+2
Chemical Names and Formulas
Cations of the Transition Elements
VIB
VIIB
VIIIB
VIIIB
VIIIB
IB
IIB
Cr+2
Cr+3
Mn+2
Mn+3
Fe+2
Fe+3
Co+2
Co+3
Ni+2
Ni+3
Cu+1
Cu+2
Ag+1
Zn+2
Au+1
Au+3
Hg+1
Hg+2
Cd+2
Chemical Names and Formulas
IA
IIA
IIIA
IVA
C-4
VA
VIA
VIIA VIIA
N-3
O-2
H-1
F-1
He
Ne
P-3
S-2
Cl-1
Ar
As-3
Se-2
Br-1
Kr
Sb-3
Te-2
I-1
Xe
At-1
Rn