Greek Prefixes and Suffixes Latin Roots Old Naming System Greek Prefixes and Suffixes Latin Roots

Introduction Before the implementation of the “Stock System of Nomenclature” (the way of writing names that you have learned in this unit), there were many different methods of naming a single compound.

for example…. The compound with the formula FeCl3 was called: iron chloride iron trichloride iron (III) chloride and “ferric chloride”

Quite simply, different labs had their own system of writing names for compounds. It made for difficulties in communication between the labs and is the reason why a “standard system” was established.

But what about that last way of naming FeCl3 ??? Where did the “ferric chloride” come from ? It turns out that one of the more “popular” methods of naming compounds involved using the Latin name of the element. Suffixes were added in order to distinguish between the various oxidation states of the transition elements.

Latin Names The symbol for iron, Fe, comes from the Latin name “ferrum” The symbol for copper, Cu, comes from the Latin name “cuprum” The symbol for lead, Pb, comes from the Latin name “plumbum” The symbol for gold, Au, comes from the Latin name “aurorum” There are others….

Greek Suffixes (and Prefixes) Suffixes (and prefixes) were used to indicate relative values of oxidation state. Remember that the transition elements have variable oxidation states. The suffix “ –ic “ was used to indicate a higher oxidation state and the suffix “ –ous “ was used to indicate a lower oxidation state.

However…. The suffixes did not tell the reader the exact value of the oxidation state…. All that was communicated was that one value was higher than the other. The reader was required to know all of the possible oxidation states for the element in question.

Here is how it works… Iron has two oxidation states in nature, it can be a +2 or a +3. Therefore, if iron is reacted with chlorine, you could get two different compounds. They would have the formulas FeCl2 and FeCl3

Naming Therefore, FeCl2 would be “ferrous chloride” The FeCl2 has iron in its +2 oxidation state which is lower than the +3 oxidation state in FeCl3. Therefore, FeCl2 would be “ferrous chloride” and the FeCl3 is “ferric chloride”

A Connection to Acids: In the discussion on writing acid names, it was offered there was a system for writing acid names for oxy-acids that involve the “modified polyatomics” It turns out that we use the Greek suffix system to describe the modified polyatomic.

Examples: Remember that H2SO4 is named sulfuric acid. It has the sulfate ion, which is one of the reference list polyatomics. The acid with the formula H2SO3 will have the acid name sulfurous acid. Remember that the suffix “-ous” is going to mean “less” or “lower”. Sulfite is “lower” than sulfate, hence the different ending to the acid name.

Summarizing some Rules for Naming Acids… An oxy-acid with an –ate polyatomic will have an acid name that ends with –ic -ate -ic An oxy-acid with an -ite polyatomic will give an acid name that ends with –ous -ite -ous An oxy-acid with a polyatomic that has a prefix will give an acid name with that same prefix. ex. “hypochlorite” “hypochlorous”