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04/25/09

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Nomenclature Flow Chart, Text Version

�Before You Begin:

To use this flow chart, you will need to be familiar with periodic law and the information found on a periodic table. You must also know the types of compounds, how to identify them, and the names of the polyatomic ions. The flow chart does not explain the nomenclature rules or give examples. It only gives the logic behind determining which set of nomenclature rules to follow.

Choose a formula to name. Begin at the top of the chart and ask yourself each of the questions. If the answer is 'yes,' follow the instructions and ask the next question. If the answer is 'no,' follow the instructions and skip to the appropriate question. If you are instructed to skip to another number, ignore all of the questions in between. Eventually you will get to a statement that will tell you which rule to apply. Stop at that point and choose a new compound to name.

Start

  1. Does the formula contain a metal? If yes, go to question 2; if no, skip to question 5.
  2. Does the formula contain square brackets? If yes, the compound is a coordination compound. STOP. You will need more information about coordination compounds than this flow chart can provide. If the answer is no, go to question 3.
  3. Does the metal have only one oxidation state (only one possible charge)? If yes, you can name the compound by naming the positive ion (same as the metal name) then the negative ion. STOP. If the answer is no, go to question 4.
  4. What is the charge of the metal ion in this particular case? Use the subscripts and the charge of the negative ion to determine this. Write the charge of the metal ion as a Roman numeral following the metal name then write the negative ion name. STOP
  5. Does the formula contain the ammonium ion, NH4+1? If yes, the name of the ionic compound is ammonium followed by the name of the negative ion. STOP. If the answer is no, the compound is not ionic. Go on to question 6.
  6. Does the formula start with H? If yes, go to question 7. If no, the compound is not an acid (at least for naming purposes). Skip to question 10.
  7. Identify the anion and its root word. Does the name of the anion end with the suffix “-ate?” If yes, the acid name follows the format “___ic acid” with the root word in the blank. STOP. If the answer is no, go on to question 8.
  8. Does the name of an anion end with the suffix “-ite?” if yes, the acid name follows the format “___ous acid” with the root word in the blank. STOP. If the answer is no, go on to question 9.
  9. The anion ends with the suffix “_ide.” Is the compound in an aqueous solution? If the answer is yes, the acid name follows the format “hydro___ic acid” with the root word in the blank. STOP. If the answer is no, go on to question 12.
  10. The compound is molecular. Does it contain carbon? If the answer is yes, go on to question 11. If the answer is no, skip to question 12.
  11. Does the compound have only one carbon atom and one other element (not hydrogen)? If yes, go to question 12. If the answer is no, the compound is organic. STOP. You will need more information about organic compounds than this flow chart can provide. If the answer is no, go on to question 13.
  12. Is the compound one of these: CO2,CO, CCl4? If yes, go on to question 13. If no, this organic compound is not one that is easy to name. STOP. You need more information about organic nomenclature.
  13. Does the compound contain only two non-metals? If the answer is yes, name the compound by naming the first element with a prefix that matches the subscript in the formula then name the second element with a prefix that matches its subscript. End the name of the second element with the suffix “-ide.” STOP. If the answer is no, the name is more complicated than the rules in this flow chart and you will need more detailed nomenclature rules. STOP.

 

4Concept Check: What is the name of HBr(aq)?

Answer: HBr is hydrobromic acid. It does not contain a metal or the NH4+1 ion, so it is not ionic (this gets us to question 5). The formula does begin with H, so it is an acid (yes to question 6). The anion is Br-1, bromide (no to questions 7 and 8).  This ends in -ide and the compound is aqueous, so it is named as an acid (yes to question 9). The format is hydro__ic acid, and the root is -brom-. The name is hydrobromic acid and we stop at this point.

 

 

 

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