Chemical Naming

Naming Binary Compounds

To name ionic compounds the names of each ion get placed together, with a polyatomic's name replacing whatever it was going to take the place of. If a polyatomic ion takes the place of the anion, the –ide rule does not happen. Here are some examples:

Acids start their formulas with H and also have their own special naming scheme, where Acid is always the second word. The anion that hydrogen is attached to determines the other word in its name:

• If the ending for the anion would be -ide it becomes Hydro____ic Acid (Example: Hydrochloric Acid is HCl)

• If the ending for the anion would be -ite it becomes ____ous Acid (Example: Sulfurous Acid is H2SO3)

• If the ending for the anion would be -ate it becomes ____ic Acid (Example: Sulfuric Acid is H2SO4)

To name covalent compounds, prefixes are used to denote how many of each element you have! The last element in a compound has its ending changed to –ide, similar to ionic compounds. 

Keep in mind the prefix mono- is not needed on the first element. In addition, prefixes are usually for nonmetals and not used to denote charge. Be careful to not mix up the usage of roman numerals and prefixes.

Putting everything together, we need to do a few things to determine the formula of a substance:

• Elements usually stand alone unless they are diatomic or a special allotrope, in which case they will be in the form of a molecule.

• When looking at 2+ different elements a compound will form. To determine what type of compound we can look at electronegativity, but as a general rule of thumb:

  • • Ionic compounds have 1 metal and 1 nonmetal. Charges need to balance out to determine the formula. Remember, you cannot just add extra electrons! You have to use the specific charges given for the atoms and add more of these atoms to make them balance out to 0.

    • Covalent compounds have only nonmetals. All nonmetals need their bonds filled, which is based on how many electrons they need to gain to behave like a noble gas.

    • Metallic compounds have only metals. They are usually treated as elements due to the strange way metallic bonds work.

• As a side note mixtures don't have specific formulas since they are made of multiple molecules, elements, and/or compounds at once! If need be we can write the formula for each individual part of a mixture, doing the above for every piece of the mixture.

Organic Molecules

Organic chemistry relates to all compounds made of organic materials. These have special naming schemes based on their structure and different atoms and are where many pharmaceuticals base their names from. When looking at an organic compound functional groups can be identified to help with their naming and understanding their functions:

Additional Resources

• Crash Course: Nomenclature

• Nomenclature Flowchart

• Another Nomenclature Flowchart

• Flowchart for Names to Formulas and Formulas to Names

• How to Use Roman Numerals in Naming

• Speed Naming Practice

Interesting Links

• What's really in pumpkin spice latte?

• The Five Reactions on Every Organic Chemist's Wish List

• Clockwork