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

Understanding how to name ionic compounds is essential in chemistry. Ionic compounds consist of a positive ion (cation) and a negative ion (anion). Cations can be metals with a positive charge or the ammonium ion (${\mathrm{NH}}_4+$), while anions are typically nonmetals or polyatomic ions with a negative charge, such as nitrate, carbonate, or phosphate ions. When naming an ionic compound, the cation is always named first and retains its elemental name. If the metal cation can have multiple charges, a Roman numeral indicates its specific charge. For example, a metal in the main group elements that has a consistent charge does not require a Roman numeral, unlike transition metals which can have multiple charges. The anion, if a nonmetal, retains its base name but changes its ending to 'ide' (e.g., chloride for chlorine). If the anion is a polyatomic ion, it keeps its given name. Remember, the base name of a nonmetal is the unchanged beginning of its name, such as 'hydrogen' for hydrogen or 'carb' for carbon. This nomenclature is crucial for correctly identifying and communicating about chemical substances.

Naming Ionic Compounds

Namely, 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 what are the components that make up an ionic compound. Now recall an ionic compound. Ionic compounds themselves contain 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 is only two that possess a positive charge, one of them being mercury one ion, but that already fits under the whole idea of being a metal.

The other polyatomic ion that is positive is the ammonium ion. And 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's a certain number of steps you have to follow in order to name the compound successfully. Now if we take a look here, step zero, Step zero is the most important thing to remember when it comes to ionic compounds. We're always going to write them as cation first followed by anion second, OK. And that's the way we kind of want to keep things consistent.

Step one we're going to start out with the cations since it's written first. With the 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 periodic table and charges. Remember, 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 of them we're talking about. Am I talking about the manganese 2 ion or am I talking about the manganese 5 ion? So again, if you don't remember this, go back to my videos on periodic table and charges. So if it possesses multiple charges, we use a Roman numeral. If the metal possesses 1 charge, just one type of charge, then we don't have to worry about a Roman numeral.

For example, aluminum. Aluminum is in Group three. 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 ID. Now recall the base name is just the beginning of the nonmetals 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 silic, nitrogen. Phosphorus is phospha. 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 selin, tellurium is tellur, and then we've covered the halogens when discussing the oxyhalogens or halogenoxy anions. So we know that these are chlor, brom, and iod. 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 says provide the name for the following compound, California and CL. All right. So California 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, they all have one charge 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 core, but then we add I'd to the end of the name.

OCAC. 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:

How do you name ionic compounds?

Naming ionic compounds involves a few simple rules. First, identify the cation (positive ion) and the anion (negative ion) in the compound. For a simple ionic compound, the name of the cation comes first, followed by the name of the anion.

1. For the cation, which is usually a metal, use the element's name. If the metal can form ions with different charges, such as iron, you must include a Roman numeral in parentheses to indicate the charge. For example, ${\mathrm{Fe}}_2+$ is iron(II), and ${\mathrm{Fe}}_3+$ is iron(III).
2. For the anion, take the root of the element's name and add the suffix '-ide'. For example, ${\mathrm{Cl}}_{-}$ becomes chloride, and $O_2-$ becomes oxide.
3. If the compound contains a polyatomic ion (ions composed of more than one atom), use the name of that ion without change. For example, ${\mathrm{NO}}_3-$ is nitrate, and ${\mathrm{SO}}_{4}2-$ is sulfate.

So, sodium chloride (${\mathrm{Na}}_{+}{\mathrm{Cl}}_{-}$) is named because ${\mathrm{Na}}_{+}$ is the cation (sodium) and ${\mathrm{Cl}}_{-}$ is the anion (chloride). For calcium nitrate (${\mathrm{Ca}}_{}\left({\mathrm{NO}}_3\right)2$), calcium is the cation, and the polyatomic ion nitrate is the anion.

When should Roman numerals be used when naming ionic compounds?

Roman numerals are used in the names of ionic compounds to indicate the charge of the metal cation when that metal can have more than one possible charge. This system is known as the Stock system. Metals such as iron (Fe), copper (Cu), lead (Pb), and tin (Sn) can exhibit multiple valences or oxidation states, so it's important to specify which one is in the compound.

For example, iron can have a charge of +2 or +3. If you have a compound with iron that has a +2 charge, it would be named iron(II) chloride, which is FeCl₂. If the iron has a +3 charge, the compound would be named iron(III) chloride, FeCl₃. The Roman numeral in the name corresponds to the positive charge of the metal cation. This naming convention helps avoid confusion and ensures that the chemical formula can be deduced from the name of the compound.

Why are prefixes not needed in naming ionic compounds?

In ionic compounds, the cations (positively charged ions) and anions (negatively charged ions) come together in ratios that balance the overall charge of the compound. Because of this, the charges of the ions determine the proportions in which they combine, and thus, the formula of an ionic compound inherently reflects the balance of charges.

Prefixes in chemical nomenclature are typically used to indicate the number of atoms of each element in molecular compounds, where the ratio of the elements can vary without the need for charge balance. However, in ionic compounds, the ratio of ions is fixed by the requirement of charge neutrality. Therefore, the name of an ionic compound doesn't need prefixes to indicate the number of ions; instead, the simple cation name followed by the anion name suffices. For example, NaCl is simply named "sodium chloride," where the ratio of sodium ions to chloride ions is always 1:1 to balance the charges, making prefixes unnecessary.

Why are prefixes not needed in naming ionic compounds?

In ionic compounds, the cations (positively charged ions) and anions (negatively charged ions) come together in ratios that balance the overall charge of the compound. Because of this, the charges of the ions determine the proportions in which they combine, and thus, the formula of an ionic compound inherently reflects the balance of charges.Prefixes in chemical nomenclature are typically used to indicate the number of atoms of each element in molecular compounds, where the ratio of the elements can vary without the need for charge balance. However, in ionic compounds, the ratio of ions is fixed by the requirement of charge neutrality. Therefore, the name of an ionic compound doesn't need prefixes to indicate the number of ions; instead, the simple cation name followed by the anion name suffices. For example, NaCl is simply named "sodium chloride," where the ratio of sodium ions to chloride ions is always 1:1 to balance the charges, making prefixes unnecessary.