Naming Covalent or Molecular Compounds

Introduction

• Covalent or molecular compounds are composed of two nonmetals.
• Nonmetals are located to the right of the staircase on the periodic table.
• These compounds are held together by covalent bonds forming molecules.
• Naming these compounds differs from naming ionic compounds (metal + nonmetal).

Steps to Name Covalent Compounds

1. Identify the Type of Compound

   • Determine if the compound is ionic or covalent based on the elements.
   • Use covalent naming for compounds with two nonmetals.

2. Basic Naming Rules

   • First Element: Use the full element name.
   • Second Element: Use the "-ide" version of the element name (same as negative ions).

3. Use of Prefixes

   • Indicate the number of atoms of each element with prefixes:
     • 1 = Mono-
     • 2 = Di-
     • 3 = Tri-
     • 4 = Tetra-
     • 5 = Penta-
     • 6 = Hexa-
     • 7 = Hepta-
     • 8 = Octa-
     • 9 = Nona-
     • 10 = Deca-

4. Special Rules and Considerations

   • Do not use "mono-" for the first element.
   • If the prefix creates awkward pronunciation (e.g., AO or OO), adjust by removing the "A" or "O" from the prefix.

Examples

• N2O3

  • First element: Nitrogen
  • Second element: Oxide
  • Name: Dinitrogen Trioxide

• P4S10

  • First element: Phosphorus
  • Second element: Sulfide
  • Name: Tetraphosphorus Decasulfide

• CF4

  • First element: Carbon (do not use "mono-")
  • Second element: Fluoride
  • Name: Carbon Tetrafluoride

• PCl5

  • First element: Phosphorus (do not use "mono-")
  • Second element: Chloride
  • Name: Phosphorus Pentachloride

• Cl2O7

  • First element: Chlorine
  • Second element: Oxide
  • Adjust for pronunciation: Dichlorine Heptoxide

• P4O6

  • First element: Phosphorus
  • Second element: Oxide
  • Adjust for pronunciation: Tetraphosphorus Hexoxide

• CO

  • First element: Carbon (do not use "mono-")
  • Second element: Oxide (prefix mono- used)
  • Adjust for pronunciation: Carbon Monoxide

Conclusion

• Follow these steps and rules to correctly name covalent compounds.
• Pay close attention to pronunciation adjustments and the special rule about "mono-" for the first element.
• With practice, naming covalent compounds will become second nature.