compounds are two or more elements that are held together by opposite charge attraction. oxygen-8...
TRANSCRIPT
Compounds are two or more elements that are held together by opposite charge attraction.
Oxygen-8Magnesium-12 8 (+)10 (-)-2 Charge
12 (+)10 (-)+2 Charge
Metal Non-metal
Metals combine with non-metals
Metals loose electrons to non-metals
They then attract because their charges will be opposite.
-3 -2 -1
Most of the negative ions have a set negative charge
Metals in groups 1A, 2A, and 3A have set positive charges when they lose electrons. So does Zn, Cd, & Ag. They are attracted to either a single non-metal ion or a polyatomic ion…+1
+2 +3
+1 +2
POLYATOMIC IONS (charged building blocks)Polyatomic ions are mostly made of two non-metals.
Ions with -1 chargeperbromate BrO4
-1
bromate BrO3-1
bromite BrO2-1
hypobromite BrO-1
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1
periodate IO4-1
iodate IO3-1
iodite IO2-1
hypoiodite IO-1
nitrate NO3-1
nitrite NO2-1
hydroxide OH-1
cyanide CN-1
acetateC2H3O2
-1
Permanganate MnO4-1
bicarbonate HCO3-1
Ions with a -2 Chargecarbonate CO3
-2
sulfate SO4-2
sulfite SO3-2
chromate CrO4-2
dichromate Cr2O7-2
oxalate C2O4-2
Ions with a -3 Charge
phosphate PO4-3
phosphite PO3-3
arsenate AsO4-3
Ions with +1 chargeammonium ion
NH4+1
Ions with -1 chargeperbromate BrO4
-1
bromate BrO3-1
bromite BrO2-1
hypobromite BrO-1
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1
periodate IO4-1
iodate IO3-1
iodite IO2-1
hypoiodite IO-1
-1
These polyatomic ions match the charge of their group
-2
These polyatomic ions match the charge of their group
Ions with a -2 Chargesulfate SO4
-2
sulfite SO3-2
Ions with a -3 Chargephosphate PO4
-3
phosphite PO3-3
-3
It is also important to memorize the oxidation of the ions that have fixed oxidation numbers (positive or negative). In particular, those from groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A and the elements: Zn, Cd and Ag. Use the following periodic chart to determine their oxidation numbers. Just click on the element symbol…
N
Elements with Fixed Oxidation Numbers
La Hf Ta Re OsCe Ba Tl Pb Bi Po At RnIr Pt Au Hg
Y Zr Nb Mo Tc RuRb Sr In Sn Sb Te I XeRh Pd Ag Cd
Sc Ti V Cr Mn FeK Ca Ga Ge As Se Br KrCo Ni Cu Zn
Al Si P S Cl ArNa Mg
B C O F NeLi Be
H H He
Ac Rf Db Sg Rh HsFr Ra Mt
+1+2 +31A
2A
8A
0-4-3-2-17A
6A5A4A3A
W
Nd Pm Sm Eu Gd TbCe Pr Yb LuDy Ho Er Tm
Np Am Cm BkTh Pa No LrCf Es Fm MdU Pu
Click on element to see its oxidation number(s)
Next Slide
Naming Ionic CompoundsThe positive ion (usually a metal) is named first while the negative ion (a non-metal or a polyatomic ion) is named last.
The charge on the negative ion is used to determine the charge on the positive ion. In-order for the total oxidation state to be zero, the total positive charge must equal the total negative charge. A simple algebraic equation can be used to determine the charge on a single metal ion. This charge is expressed as a “Roman Numeral” in parenthesis that immediately follows the name of the metal.
CuSO4
Cu?SO4-2
x +(-2)=0
X = 2
Copper (II) Sulfate
Naming Ionic CompoundsThe positive ion (usually a metal) is named first while the negative ion (a non-metal or a polyatomic ion) is named last.
The charge on the negative ion is used to determine the charge on the positive ion. In-order for the total oxidation state to be zero, the total positive charge must equal the total negative charge. A simple algebraic equation can be used to determine the charge on a single metal ion. This charge is expressed as a “Roman Numeral” in parenthesis that immediately follows the name of the metal.
Cu2SO4
Cu2+xSO4
-2
2x +(-2)=0
x = 1
Copper (I) Sulfate
Naming Ionic Compounds• If the positive ion is one that has a fixed oxidation
number then no Roman Numeral is used. • Everyone should know the charge of fixed ions.
These include metals in group 1A, 2A and the specific metals: Al, Zn, Cd & Ag (zinc, cadmium and silver).
CaSO4
Calcium Sulfate
No Roman Numeral
Examples #1- Formulas to Names
CuSO3
copper
I’m a polyatomi
c ion
1. Write the names of the ions
Final Name
sulfite(II)
x
X + (- 2) = 0
X = +2
Cu SO3
= 0
You must know the charge on the sulfite ion is -2
The sum of the positive and negative charges must equal zero
2. Determine the charge of the positive ion
-
2
+2 +2
Next
+2
Examples #2- Formulas to Names
KMnO4
potassium
I’m a polyatomi
c ion
1. Write the names of the ions
Final Name
permanganate
If the positive ion has a fixed charge, you are finished.
Examples #3- Formulas to Names
NH4NO3
ammonium
I’m a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
nitrate
If the positive ion has a fixed charge, you are finished.
Examples #4- Formulas to Names
SnF2
tin
I’m not a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
fluoride(II)
Snx (F-1)2 = 0
X + 2(-1) = 0
X = +2
Examples #5- Formulas to Names
Ba(ClO4)2
barium
I’m a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
perchlorateIf the positive ion has a fixed charge, you are finished.
Examples #6- Formulas to Names
Cu2S
copper
I’m not a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
sulfide(I)
2Cux (S)-2 = 0
2X + (-2) = 0
X = +1
Examples #6- Formulas to Names
Cu2S
copper
1.Write the names of the ions
Final Name
sulfide(I)
x
2X + (- 2) = 0
2X = +2
(Cu )2 S
You must know the charge on the sulfide ion is -2
The sum of the positive and negative charges must equal zero
2. Determine the charge of the positive ion
-2
+2 +2
Next
+1
2 2
X = +1
Examples #7- Formulas to Names
Na2Cr2O7
sodium
I’m a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
dichromate(I)
2(Nax)(Cr2O7)-2 = 0
2X + (-2) = 0
X = +1
If the positive ion has a fixed charge, it is not shown
FePO3 .3H2O
Examples #9- Formulas to Names
iron
I’m a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name phosphite(III)
Fex (PO3 -3) = 0
X + (-3) = 0
X = +3
hydrate
I’m a hydrated compound, this
part will be named last
.3H2O3
tri
Examples #10- Formulas to Names
LiCN
lithium
I’m a polyatomi
c ion
2. Determine the charge of the positive ion
1. Write the names of the ions
Final Name
cyanideIf the positive ion has a fixed charge, you are finished.
Writing Ionic Formulas• It is easier to write the formula of an
ionic compound from its name than the reverse.
• The oxidation number of the negative ion must be memorized in all cases. Refer to the table of polyatomic ions.
aluminum chloride
Example #1-Names to Formulas
AlCl3
2. Determine number of ions
1. Write symbols of elements
Final Formula
Al Cl-1
1
If there is only one atom the “1” is not shown
+3
If there is no Roman Numeral, you need to know the fixed oxidation number of the positive ion.
Next
Example #2-Names to Formulas
cobalt(II) bromate
Co BrO3
2. Determine number of ions
1. Write symbols of elements
Final Formula
(Co+2)(BrO3-1)= 0
(BrO3)
2Next
Example #3-Names to Formulas
nickel(III) acetate
Ni C2H3O2
2. Determine number of ions
1. Write symbols of elements
Final Formula
(Ni+3)x(C2H3O2-1)y
= 0
(C2H3O2)3
Next
Example #4-Names to Formulas
lithium phosphate
Li PO4
2. Determine number of ions
1. Write symbols of elements
Final Formula
(Li )x(PO4-3)y
= 0
3
+1
(PO4)If there is no Roman Numeral, you need to know the fixed oxidation number of the positive ion.
Next
Practice Problems
By now you should have an idea of what is expected when naming covalent binary compounds using prefixes.
In order to master this naming system you need to practice until you feel proficient in naming compounds using prefixes.
Practice Problem #1Fe(NO3)3
Choose the correct name for the compound
1. Iron trinitrate
2. iron(I) nitrate
3. iron(III) nitrite
4. iron(III) nitrate
5. none of the abovenext
problemPolyatomic
IonsPeriodic Chart
Practice Problem #2sodium chlorite
Choose the correct formula for the compound
1. NaCl
2. NaClO
3. NaClO2
4. Na(ClO)2
5. none of the above
EndPeriodic Chart
POLYATOMIC IONS
Ions with -1 chargeperbromate BrO4
-1
bromate BrO3-1
bromite BrO2-1
hypobromite BrO-1
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1
periodate IO4-1
iodate IO3-1
iodite IO2-1
hypoiodite IO-1
nitrate NO3-1
nitrite NO2-1
hydroxide OH-1
cyanide CN-1
thiocyanate SCN-1
acetate C2H3O2-1
Permanganate MnO4
-1
bicarbonate HCO3-1
Ions with a -2 Chargecarbonate CO3
-2
phthalate C8H4O4-2
sulfate SO4-2
sulfite SO3-2
chromate CrO4-2
dichromate Cr2O7-2
oxalate C2O4-2
peroxide O2-2
Ions with a -3 Chargephosphate PO4
-3
phosphite PO3-3
arsenate AsO4-3
Ions with +1 chargeammonium ion
NH4+1
return
N
Oxidation Numbers (most common)
La Hf Ta Re OsCe Ba Tl Pb Bi Po At RnIr Pt Au Hg
Y Zr Nb Mo Tc RuRb Sr In Sn Sb Te I XeRh Pd Ag Cd
Sc Ti V Cr Mn FeK Ca Ga Ge As Se Br KrCo Ni Cu Zn
Al Si P S Cl ArNa Mg
B C O F NeLi Be
H H He
Ac Rf Db Sg Rh HsFr Ra Mt
+1+2+31A
2A
8A
0-4-3-2-17A
6A5A4A3A
W
Nd Pm Sm Eu Gd TbCe Pr Yb LuDy Ho Er Tm
Np Am Cm BkTh Pa No LrCf Es Fm MdU Pu
Click on element to see its oxidation number(s)
+1 +2 +2 +3 +2 +4
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