Molecular Compounds and Nomenclature Lesson 7 September 2nd, 2010

Molecular Nomenclature Most compounds that you find everyday are molecular compounds, not ionic. Sugar (molecular) for example has similar physical properties as salt (ionic) but they are very different in reality.

For example if you were to dissolve salt in water it would make the water conductive to electricity were the sugar would not. This is due to the fact that ionic compounds are made of ions which can conduct electricity. Molecular compounds on the other hand are not made of ions. They do not lose or gain electrons, they share electrons.

Ionic compounds can only bond to non metals in so many ways. Ex for every Ca we can only bond 2 F to it. Molecular compounds do not work that way. Molecular compounds can have various numbers of atoms bonded together to create various molecules. Ex. NO, NO2, N2O2, etc. Due to this method of bonding there are thousands more molecular compounds than there are ionic compounds.

Molecular Compounds are made of two or more Non-metals which share pairs of electrons to form bonds. Each pair of shared electrons is called a Covalent Bond.

The names of molecular compounds often contain prefixes The names of molecular compounds often contain prefixes. The prefixes are used to count the number of atoms in the molecule. This is important as molecular compounds containing 2 elements can have different combinations of atoms which have different properties.

# of atoms 1 2 3 4 5 6 7 8 9 10 Prefix Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca

Naming Binary Molecular Compounds: IUPAC Write down the name of the first element. If there is more than one atom of this element attach a Greek prefix. (if there is only one atom do not attach the prefix) Attach a Greek prefix (relating to the number of atoms) to the second elements name and add -ide. Example: CO = Carbon monoxide CO2 = Carbon dioxide

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