Naming Ionic Compounds - Online Tutor, Practice Problems & Exam Prep

Understanding ionic compounds is crucial in chemistry, as they consist of cations (positive ions) and anions (negative ions). Cations can be metals or polyatomic ions like ammonium (NH₄⁺), while anions are typically nonmetals or negatively charged polyatomic ions. When naming ionic compounds, always list the cation first, followed by the anion. If the metal has multiple charges, use Roman numerals to indicate its charge. Nonmetals change their ending to "-ide," while polyatomic ions retain their names. Mastering these naming conventions is essential for success in chemistry.

Naming Ionic Compounds

Naming ionic compounds is going to be an incredibly important skill that you'll have to utilize for the remainder of your chemistry career. Now before we can name ionic compounds, it's first important to understand the components that make up an ionic compound. Now recall, an ionic compound itself contains a positive ion called a cation. And one way to remember that cations are positive is here, this t can be seen as a positive charge associated with them, and this positive ion is connected to a negative ion called an anion. This is important to recall because a lot of times we may mistakenly say that an ionic compound is simply a metal with a nonmetal. That is not true. An ionic compound fundamentally is a positive ion with a negative ion. The cation could be represented by a metal, but it could also be represented by a polyatomic ion that possesses a positive charge. And remember, the polyatomic ions, there's only 2 that possess a positive charge. One of them being mercury 1 ion, but that already fits under the whole idea of being a metal. The other polyatomic ion that is positive is the ammonium ion. Remember, the ammonium ion is NH4+. So our cations are a metal with a positive charge or the ammonium ion which has a positive charge, And the anion is represented by a nonmetal or also a polyatomic ion that possesses a negative charge. So remember, a lot of the other polyatomic ions that possess negative charges, you have your nitrate ion, your carbonate ion, your phosphate ion. When it comes to an ionic compound, to be able to spot them, you have to remember they are a positive ion connected to a negative ion. So as we go into naming them, just remember these fundamental components that make them up.

Naming Ionic Compounds

When it comes to naming an ionic compound, there are certain steps you have to follow in order to name the compound successfully. Now, if we take a look here, step 0. Step 0 is the most important thing to remember. When it comes to ionic compounds, we're always going to write them with the cation first, followed by the anion second. And that's the way we want to keep things consistent. Step 1, we're going to start out with a cation since it's written first. With a cation, the metal always keeps its name and is written first.

Now, part of this deals with the charge. If the metal possesses multiple charges, we must use a Roman numeral to describe its positive charge. So remember, if you don't recall this, go back to our videos on the periodic table and charges. The main group elements, for the most part, possess one type of charge, so they wouldn't require a Roman numeral. It's the transition metals, for the most part, that possess multiple charges. Because of that, we have to specify which one we're talking about. Am I talking about the manganese 2 ion or the manganese 5 ion? So again, if you don't remember this, go back to my videos on the periodic table and charges. If it possesses multiple charges, we use a Roman numeral. If the metal possesses one charge, just one type of charge, then we don't have to worry about a Roman numeral. For example, aluminum. Aluminum is in group 3. Group 3 has a charge of plus three. Aluminum is not going to have any other type of positive charge, so I don't have to give it a Roman numeral.

Now, for the anion, if a nonmetal is used, it keeps its base name but has its ending changed to -ide. Recall, the base name is just the beginning of the nonmetal's name that is unchanged. In the next video, we're going to take a look at the different types of nonmetals and what exactly are their base names following this definition. So click on to the next video and let's take a look at some base names of nonmetals.

Naming Ionic Compounds

Now remember, the base name is just the beginning of the nonmetal's name that is unchanged. So if we take a look here, we have our nonmetals, and we try to group them as best as we can in terms of the periodic table. So we have in group 1a, hydrogen, 3a, boron. These are in 4a. These are in 5a. These are in 6a, and of course, our halogens in 7a. Now remember, the base name again is the beginning of the nonmetal's name that is unchanged. So for hydrogen, its base name is hydro. Boron, it's bor. Carbon is carb. Silicon is sil. Nitrogen is nitro. Phosphorus is phospho. Oxygen is just ox. Now again, we can just add suffix endings to them, but these are just the base names. Sulfur is sulf, then we have selenium which is selen, tellurium is tellur, and then we've covered the halogens when discussing the oxyhalogens or halogenoxy anions. So we know that this is for chlorine, bromine, and iodine. So these will be the base names for nonmetals when it comes to ionic compounds. Now step 3 is just if we're dealing with a polyatomic ion in any way, if it's present, it always just keeps its name. So if our ionic compound possesses a phosphate group, then it's just phosphate. Now keep these steps in mind when we're presented with any type of ionic compound and asked to determine its name.

Naming Ionic Compounds Example 1

In this example question, it asks for the name of the following compound, Ca and Cl. Alright, so Ca is calcium and Cl is chlorine. We know that the metal keeps its name and is written first, so we have calcium. But we have to think about, does calcium possess multiple charges? Calcium is in group 2A on the periodic table. Remember, metals in group 2A all have a charge of +2. Because calcium possesses only one charge, it does not require a Roman numeral. So its name would just be calcium. Then we have chlorine. Remember, for the nonmetal, we keep its base name which is chlor, but then we add "ide" to the end of the name. So CaCl₂ would be called calcium chloride.

Provide the name for the following compound:Al(BrO₄)₃

• A. aluminum hypobromite
• B. aluminum bromite
• C. aluminum bromide
• D. aluminum bromate
• E. aluminum perbromate

Provide the name for the following compound:CoCO₃

• A. cobalt carbonate
• B. cobalt (II) carbonate
• C. cobalt carbonite
• D. cobalt (III) carbonite

Here’s what students ask on this topic:

What are the steps to name an ionic compound?

To name an ionic compound, follow these steps:

1. Write the cation (positive ion) first, followed by the anion (negative ion).

2. For the cation, if it is a metal, use its elemental name. If the metal has multiple possible charges, indicate the charge with a Roman numeral in parentheses.

3. For the anion, if it is a nonmetal, take the base name of the element and change the ending to '-ide'.

4. If the anion is a polyatomic ion, retain its name without any changes.

Example: NaCl is named sodium chloride, and Fe₂(SO₄)₃ is named iron(III) sulfate.

How do you determine the charge of a transition metal in an ionic compound?

To determine the charge of a transition metal in an ionic compound, follow these steps:

1. Identify the anion and its charge. For example, in FeCl₃, Cl is the anion with a charge of -1.

2. Multiply the anion's charge by the number of anions present. In FeCl₃, there are three Cl^- ions, so the total negative charge is -3.

3. The total positive charge must balance the total negative charge. Therefore, the charge on Fe must be +3 to balance the -3 from the Cl ions.

4. Indicate the charge of the transition metal using a Roman numeral in parentheses. Thus, FeCl₃ is named iron(III) chloride.

Why do some ionic compounds require Roman numerals in their names?

Roman numerals are used in the names of ionic compounds to indicate the charge of metals that can form more than one type of positive ion. This is common with transition metals. For example, iron can form Fe²⁺ and Fe³⁺ ions. To distinguish between these, we use Roman numerals: FeCl₂ is iron(II) chloride, and FeCl₃ is iron(III) chloride. This helps avoid confusion and ensures the correct compound is identified.

What is the difference between a cation and an anion?

A cation is a positively charged ion, while an anion is a negatively charged ion. Cations are typically formed by metals losing electrons, resulting in a positive charge. For example, Na⁺ is a cation. Anions are usually formed by nonmetals gaining electrons, resulting in a negative charge. For example, Cl^- is an anion. In ionic compounds, cations and anions combine to form neutral compounds, such as NaCl (sodium chloride).

How do you name ionic compounds with polyatomic ions?

When naming ionic compounds with polyatomic ions, follow these steps:

1. Write the name of the cation first. If the cation is a metal with multiple charges, indicate its charge with a Roman numeral.

2. Write the name of the polyatomic ion as it is, without changing its ending.

For example, in NaNO₃, Na is the cation (sodium), and NO₃ is the polyatomic ion (nitrate). The compound is named sodium nitrate. In Fe(OH)₃, Fe is the cation (iron) with a charge of +3, and OH is the polyatomic ion (hydroxide). The compound is named iron(III) hydroxide.