Writing Formulas

Chapter 6(Chapter 9)

Rules for Writing Chemical Formulas Name begins with a metal Name does NOT begin with a metal

‘ACID’ in the name No ACID in Name

1) Write the metal symbol/charge

2) Write the non metal symbol/charge

3) Add subscripts if necessary to make it neutral (criss-cross)

Ends with -IDE Ends with –ATE/-ITE

1) Write each element symbol [NO CHARGES USED HERE] [NO Polyatomic IONS HERE]

2) The Prefix IS the subscript

(mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca)

‘HYDRO’ in front No ‘HYDRO’ in front

1) Write H+1

2) Write non metal symbol/charge

3) Add subscripts if necessary to make it neutral (criss-cross)

Name ends with -IC

Name ends with - OUS

1) Write H+1

2)Write Polyatomic ion that ends with -ATE

3) Add subscripts if needed to make it neutral

1) Write H+1

2)Write Polyatomic ion that ends with -ITE

3) Add subscripts if needed to make it neutral

Classic Names: add –OUS for lower charge/ -IC for higher charge to these roots

(Ammonium acts like a metal)

*These metals use a Roman Numeral after their name to indicate it’s charge

Copper (I) – Cu+1

Copper (II)- Cu+2

Mercury(I) – Hg2+2

Mercury(II) – Hg+2

Iron(II) – Fe+2

Iron (III) – Fe+3

Chromium (II) – Cr+2

Chromium(III) – Cr+3

Manganese(II) – Mn+2

Manganese(III) – Mn+3

Cobalt(II) – Co+2

Cobalt(III) – Co+3

Lead(II) – Pb+2

Lead(IV) – Pb+4

Tin(II) – Sn+2

Tin(IV) – Sn+4

Cupr -Mercur -

Ferr -Chrom -Mangan -Cobalt -

Plumb -Stann -

1) Write the metal symbol/charge

2) Write the polyatomic ion/charge

3) Add subscripts/parenthesis if necessary to make it neutral (criss-cross)

Rules for Writing Chemical Formulas

1. All molecules have a neutral charge

2. Subscripts are used when individual charges are not the same

3. Parenthesis are used ONLY WITH POLYATOMIC IONS that need a subscript to make it neutral

4. Two non metals have prefixes to indicate their subscripts

5. The charges of representative elements are known to be:

Charges for metals and non metals

K2SO4

Potassium sulfate

BaC2O4

Barium oxalate

HClO2

Chlorous acid

(NH4)2SO3

Ammonium sulfite

MgCO3

Magnesium carbonate

CBr4

Carbon tetrabromide

P2O5

Diphosphorous pentoxide

HNO3

Nitric Acid

NaHSO3

Sodium hydrogen sulfite

H2C2O4

Oxalic acid

Al(C2H3O2) 3

Aluminumacetate

Mg(OH)2

Magnesium hydroxide

H3PO3

Phosphorous Acid

HF

Hydrofluoric Acid

Zn(ClO)2

Zinc hypochlorite

LiH

Lithium hydride

HClO3

Chloric acid

Rb2S

Rubidium sulfide

SrCrO4

Strontium chromate

KMnO4

Potassium permanganate

NaCN

Sodium cyanide

Ca(HSO3)2

Calcium hydrogen sulfite

Ba(NO3)2

Barium nitrate

H3PO3

Phosphorous acid

Ag2CrO4

Silver chromate

ZnCO3

Zinc carbonate

stop

SO3

Sulfur trioxide

BeSe

Beryllium selenide

AlN

Aluminum nitride

NH4C2H3O2

Ammonium acetate

PCl3

Phosphorous trichloride

K2HPO3

Potassium hydrogen phosphite

H2SO4

Sulfuric acid

H2S

Hydrosulfuric acid

(NH4)2C2O4

Ammonium oxalate

HNO2

Nitrous acid

Al2(SO4)3

Aluminum sulfate

LiClO2

Lithium chlorite

Ag2Cr2O7

Silver dichromate

Hl

Hydroiodic acid

NaClO

Sodium hypochlorite

NI3

Nitrogen triodide

H2CrO4

Chromic acid