The document explains how to name and write formulas for binary and ternary ionic compounds, emphasizing the importance of cations and anions. It describes the criss-cross method for determining formulas, the conversion of anion names by changing their endings, and includes examples like rubidium chloride and sodium nitrate. Additionally, it mentions polyatomic ions and encourages further study of common cations and anions.

1. First, let's start with naming binary ionic compounds. A binary ionic compound
has one metal and one nonmetal present in the compound. Let's consider my username
(rubidium.chloride) as an example. Rubidium chloride, or RbCl, is a binary ionic compound.
The metal here is Rb (rubidium, group 1A) and the nonmetal is Cl (chlorine, group 7A). When
you name binary ionic compounds, you mention the cation (positively charged ion) first (usually
metals, those elements that appear on the left side of the periodic table have the tendency to form
positively-charged ions). Then mention the anion (negatively charged ion). The cation is
rubidium (Rb). We mention it thus: Rubidium The anion is chlorine. When we write the name
of the anion [alongside with the cation], we drop the ending -ine (or whatever ending it may
have) and replace it with -ide. So chlorine now becomes chlor + ide = chloride. Therefore, the
name of the compound is Rubidium Chloride. When you write the formulas of binary ionic
compounds, you use the criss-cross method. Here's how it works: Rubidium has a charge of +1.
Chlorine has a charge of -1. You interchange the charges of both ions. These charges, when
interchanged, become the subscripts of the elements in the compound. Hence, the compound
now looks Rb1Cl1. Since the subscripts are all 1, we can remove them and write the formula as
RbCl. Here's another example: Give the formula of the compound magnesium chloride. Mg
has a charge of +2. Chlorine has a charge of -1. When you interchange the respective charges of
magnesium and chlorine, we get the following formula: Mg1Cl2 We simplify this as MgCl2. A
list of the common cations and ions is found at the back page or on the chapter of naming
chemical compounds of your chemistry book. Take time to know them by heart. But what if...
you've got a compound named sodium nitrate. Ok. The formula is NaNO3. How did I know?
Sodium nitrate is an example of a ternary ionic compound. A ternary ionic compound has two or
more elements present in it. In this case, there are 3 (Na, N and O). The naming system of
ternary ionic compounds is the same as that of binary ionic compounds. Let's name the
participating ions: Na+ NO3- NO3- is the formula for the polyatomic ion (two or more
elements joined together sharing a common charge; they act as one unit when they combine with
other elements) nitrate. We interchange the charges of sodium and nitrate. Interchanging them
gives us the formula NaNO3 To name this formula, just combine the name of the cation and
anion together. In this case, it is sodium nitrate. What if we have a formula like this? Ba(OH)2
Don't worry. This is just barium hydroxide. Let's analyze why this came about. The charge of
Ba is +2 and hydroxide (OH-) is -1. When you combine them together by interchanging
subscripts, we get the following: BaOH2 Wait. The formula doesn't make sense. H is not the
only atom having two of its kind, but O too. So we put parentheses around hydroxide to indicate
that there are two units of the hydroxide ion, each of which has two O and H atoms respectively.
We now have the formula Ba(OH)2. Again, review the list of common polyatomic cations and
anions. So far there are two polyatomic cations: hydronium (H3O+) and ammonium (NH4+).

2. This can be found in your chem book and in the net. There are still lots of stuff related to this,
most of which are very basic, and I don't have the space to tackle all of them here. Read your
chem book or surf the net for more info. You can ask your chem teacher and friends for help,
too.
Solution
First, let's start with naming binary ionic compounds. A binary ionic compound
has one metal and one nonmetal present in the compound. Let's consider my username
(rubidium.chloride) as an example. Rubidium chloride, or RbCl, is a binary ionic compound.
The metal here is Rb (rubidium, group 1A) and the nonmetal is Cl (chlorine, group 7A). When
you name binary ionic compounds, you mention the cation (positively charged ion) first (usually
metals, those elements that appear on the left side of the periodic table have the tendency to form
positively-charged ions). Then mention the anion (negatively charged ion). The cation is
rubidium (Rb). We mention it thus: Rubidium The anion is chlorine. When we write the name
of the anion [alongside with the cation], we drop the ending -ine (or whatever ending it may
have) and replace it with -ide. So chlorine now becomes chlor + ide = chloride. Therefore, the
name of the compound is Rubidium Chloride. When you write the formulas of binary ionic
compounds, you use the criss-cross method. Here's how it works: Rubidium has a charge of +1.
Chlorine has a charge of -1. You interchange the charges of both ions. These charges, when
interchanged, become the subscripts of the elements in the compound. Hence, the compound
now looks Rb1Cl1. Since the subscripts are all 1, we can remove them and write the formula as
RbCl. Here's another example: Give the formula of the compound magnesium chloride. Mg
has a charge of +2. Chlorine has a charge of -1. When you interchange the respective charges of
magnesium and chlorine, we get the following formula: Mg1Cl2 We simplify this as MgCl2. A
list of the common cations and ions is found at the back page or on the chapter of naming
chemical compounds of your chemistry book. Take time to know them by heart. But what if...
you've got a compound named sodium nitrate. Ok. The formula is NaNO3. How did I know?
Sodium nitrate is an example of a ternary ionic compound. A ternary ionic compound has two or
more elements present in it. In this case, there are 3 (Na, N and O). The naming system of
ternary ionic compounds is the same as that of binary ionic compounds. Let's name the
participating ions: Na+ NO3- NO3- is the formula for the polyatomic ion (two or more
elements joined together sharing a common charge; they act as one unit when they combine with
other elements) nitrate. We interchange the charges of sodium and nitrate. Interchanging them
gives us the formula NaNO3 To name this formula, just combine the name of the cation and
anion together. In this case, it is sodium nitrate. What if we have a formula like this? Ba(OH)2
Don't worry. This is just barium hydroxide. Let's analyze why this came about. The charge of

3. Ba is +2 and hydroxide (OH-) is -1. When you combine them together by interchanging
subscripts, we get the following: BaOH2 Wait. The formula doesn't make sense. H is not the
only atom having two of its kind, but O too. So we put parentheses around hydroxide to indicate
that there are two units of the hydroxide ion, each of which has two O and H atoms respectively.
We now have the formula Ba(OH)2. Again, review the list of common polyatomic cations and
anions. So far there are two polyatomic cations: hydronium (H3O+) and ammonium (NH4+).
This can be found in your chem book and in the net. There are still lots of stuff related to this,
most of which are very basic, and I don't have the space to tackle all of them here. Read your
chem book or surf the net for more info. You can ask your chem teacher and friends for help,
too.