There are four naming systems you should familiarize yourself with to succeed on the SAT II Chemistry exam. The trick is recognizing which naming system to use. Here are the guidelines:

It is also essential that you memorize some common polyatomic ions. Polyatomic ions behave as a unit. If you need more than one of them, enclose them in parentheses when you write formulas. You need to know their names, formulas, and charges. If you learn the nine that follow, you can get many others from applying two simple patterns.

How do you know it’s an acid? The compound’s formula begins with an H, and water doesn’t count! Naming acids is extremely easy if you know your polyatomic ions. There are three rules to follow:

Acids have enough H⁺ added to the anion to make the compound neutral. Supply either the acid’s name or its formula to complete the table below:

How do you know it’s organic? The formula will start with a C followed by H’s. Most of the organic carbons you will encounter will be either hydrocarbons or alcohols, and luckily for you, these are the simplest of all to name. Learn the list of prefixes in the table following this section: they correspond to the number of carbons present in the compound. The following silly statement will help you remember the order of the first four prefixes since they are not ones you are familiar with: “Me eat peanut butter.” This corresponds to meth-, eth-, prop-, and but-, which correspond to one, two, three, and four carbons, respectively.

Now that we have a stem, we need an ending. There are three common hydrocarbon endings; the ending changes depending on the structure of the molecule:

For any hydrocarbon, you can remove one H and replace it with a hydroxyl group, or —OH group, to form an alcohol. Do not be fooled—this looks like a hydroxide group but isn’t! The OH does not make this hydrocarbon an alkaline or basic compound, nor do you name it as a hydroxide! C₂H₆ is ethane, while C₂H₅OH is ethanol. Fill in the missing formulas and names for each compound in the table:

How will you know a compound is ionic? You’ll know because the formula will begin with a metal cation or the ammonium cation. Formulas often end with a polyatomic anion. If only two elements are present, they are usually from opposite sides of the periodic table, like in KCl. If the metal is one of the transition metals, be prepared to use a Roman numeral to indicate which oxidation state the metal is exhibiting. Silver, cadmium, and zinc are exceptions to the Roman numeral rule! First, let’s name the ions.

Naming ionic compounds: The positive ion name is given first (remember, if it’s a transition metal, the Roman numeral indicating its charge is part of its name), followed by the name of the negative ion. No prefixes are used.

How will you know if it’s a molecular compound? Well, it will be a combination of nonmetals, both of which lie near each other on the periodic table. Use the following set of prefixes, and don’t forget the -ide ending to the name.

If the second element’s name begins with a vowel, the a at the end of the prefix is usually dropped. N₂O₅ is dinitrogen pentoxide, not dinitrogen pentaoxide. PCl₅ is phosphorous pentachloride, not phosphorous pentchloride.