Chemical Formula and Construction

• Chemical Formula


  • the chemical formula of a substance shows the elements that make up the substance and the number of atoms of each constituent element
• Chemical Equations for ionic compounds

  
  

  • the valency of an ion can be derived from the charge of the ion
  • charge of cation an anion in an ionic compound must be balanced
• Polyatomic ions

  • ammonium NH4 +
  • hydroxide OH -
  • nitrate NO3 -
  • carbonate CO3 2-
  • sulfate SO4 2-
  • phosphate PO4 3-
• Chemical formula for covalent compounds

  • hydrogen is written after the chemical symbol of elements in group 14 and 15
  • hydrogen is written before the chemical symbol of elements in group 16 and 17
  • mono : 1
  • di : 2
  • tri : 3
  • tetra : 4