Chemical Formula Writing and Nomenclature

Formula Writing: Valency & Ion Cross Multiplication

Rules for Writing Chemical Formulae (Examples)

• Magnesium Chloride:
  • Elements: Mg, Cl
  • Ions: $Mg^{+2}$, $Cl^{-1}$
  • Formula: $MgCl_2$
• Aluminium Oxide:
  • Elements: Al, O
  • Ions: $Al^{+3}$, $O^{-2}$
  • Formula: $Al<em>2O</em>3$
• Sodium Oxide:
  • Elements: Na, O
  • Ions: $Na^{+1}$, $O^{-2}$
  • Formula: $Na_2O$
• Potassium Oxide:
  • Elements: K, O
  • Ions: $K^{+1}$, $O^{-2}$
  • Formula: $K_2O$
• Aluminium Chloride:
  • Elements: Al, Cl
  • Ions: $Al^{+3}$, $Cl^{-1}$
  • Formula: $AlCl_3$
• Magnesium Bromide:
  • Elements: Mg, Br
  • Ions: $Mg^{+2}$, $Br^{-1}$
  • Formula: $MgBr_2$
• Iron (II) Oxide:
  • Elements: Fe, O
  • Ions: $Fe^{+2}$, $O^{-2}$
  • Formula: $FeO$
• Magnesium Sulfide:
  • Elements: Mg, S
  • Ions: $Mg^{+2}$, $S^{-2}$
  • Formula: $MgS$
• Copper Fluoride:
  • Elements: Cu, F
  • Ions: $Cu^{+1}$, $F^{-1}$
  • Formula: $CuF$
• Lithium Iodide:
  • Elements: Li, I
  • Ions: $Li^{+1}$, $I^{-1}$
  • Formula: $LiI$
• Barium Bromide:
  • Elements: Ba, Br
  • Ions: $Ba^{+2}$, $Br^{-1}$
  • Formula: $BaBr_2$

Worksheet: Binary Compounds (Part 1)

• Magnesium Chloride: $MgCl_2$
• Sodium Oxide: $Na_2O$
• Copper Oxide: $CuO$
• Aluminium Oxide: $Al<em>2O</em>3$

Valency Table & Polyatomic Ions

• Nitrite: $NO_2^{-1}$
• Nitrate: $NO_3^{-1}$
• Carbonate: $CO_3^{-2}$
• Hydrogen Carbonate: $HCO_3^{-1}$
• Hypochlorite: $ClO^{-1}$
• Chlorite: $ClO_2^{-1}$
• Chlorate: $ClO_3^{-1}$
• Perchlorate: $ClO_4^{-1}$
• Hydroxide: $OH^{-1}$
• Acetate: $C<em>2H</em>3O_2^{-1}$
• Cyanide: $CN^{-1}$
• Permanganate: $MnO_4^{-1}$
• Phosphate: $PO_4^{-3}$
• Dichromate: $Cr<em>2O</em>7^{-2}$
• Hydrogen Phosphate: $HPO_4^{-2}$
• Dihydrogen Phosphate: $H<em>2PO</em>4^{-1}$
• Chromate: $CrO_4^{-2}$
• Peroxide: $O_2^{-2}$
• Sulfate: $SO_4^{-2}$
• Hydrogen Sulfate (Bisulfate): $HSO_4^{-1}$

Worksheet: Binary Compounds (Part 2)

• Lead Iodide:
  • Elements: Pb, I
  • Ions: $Pb^{+2}$, $I^{-1}$
  • Formula: $PbI_2$
• Iron (III) Sulfide:
  • Elements: Fe, S
  • Ions: $Fe^{+3}$, $S^{-2}$
  • Formula: $Fe<em>2S</em>3$
• Magnesium Oxide:
  • Elements: Mg, O
  • Ions: $Mg^{+2}$, $O^{-2}$
  • Formula: $MgO$
• Rubidium Bromide:
  • Elements: Rb, Br
  • Ions: $Rb^{+1}$, $Br^{-1}$
  • Formula: $RbBr$
• Strontium Chloride:
  • Elements: Sr, Cl
  • Ions: $Sr^{+2}$, $Cl^{-1}$
  • Formula: $SrCl_2$
• Caesium Selenide:
  • Elements: Cs, Se
  • Ions: $Cs^{+1}$, $Se^{-2}$
  • Formula: $Cs_2Se$
• Calcium Arsenide:
  • Elements: Ca, As
  • Ions: $Ca^{+2}$, $As^{-3}$
  • Formula: $Ca<em>3As</em>2$
• Radium Polonide:
  • Elements: Ra, Po
  • Ions: $Ra^{+2}$, $Po^{-2}$
  • Formula: $RaPo$
• Gallium Fluoride:
  • Elements: Ga, F
  • Ions: $Ga^{+3}$, $F^{-1}$
  • Formula: $GaF_3$
• Scandium (III) Bromide:
  • Elements: Sc, Br
  • Ions: $Sc^{+3}$, $Br^{-1}$
  • Formula: $ScBr_3$
• Chromium Oxide:
  • Elements: Cr, O
  • Ions: $Cr^{+3}$, $O^{-2}$
  • Formula: $Cr<em>2O</em>3$
• Strontium Iodide:
  • Elements: Sr, I
  • Ions: $Sr^{+2}$, $I^{-1}$
  • Formula: $SrI_2$
• Lithium Arsenide:
  • Elements: Li, As
  • Ions: $Li^{+1}$, $As^{-3}$
  • Formula: $Li_3As$