By John Weide

with modifications by Ken Costello

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

+1+2 +3

+1 +2

-3 -2-1

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 the single element

-2

These polyatomic ions match the charge of the single element

Ions with a -2 Chargesulfate SO4

-2

sulfite SO3-2

Ions with a -3 Chargephosphate PO4

-3

phosphite PO3-3

-3

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

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

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 #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

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.

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

next problem

PrefixesPeriodic 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

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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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