Fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table:
| cation | anion | empirical formula | name of compound |
|---|---|---|---|
| [tex]$Sr ^{2+}$[/tex] | [tex]$P ^{3-}$[/tex] | | |
| [tex]$Sr ^{2+}$[/tex] | [tex]$O ^{2-}$[/tex] | | |
| [tex]$Sr ^{2+}$[/tex] | [tex]$s ^{2-}$[/tex] | | |
| [tex]$Sr ^{2+}$[/tex] | [tex]$N ^{3-}$[/tex] | | |
Answer (1)
Determine the ratio of ions needed to achieve a neutral compound.
Write the empirical formula with the cation first.
Name the compound by combining the cation name with the anion name, modified to end in '-ide'.
The empirical formulas and names are: S r 3 P 2 (Strontium phosphide), S r O (Strontium oxide), S r S (Strontium sulfide), S r 3 N 2 (Strontium nitride).
Explanation
Problem Analysis We are given a table with cations and anions, and we need to determine the empirical formula and name of the ionic compound formed by each cation-anion pair. The cation is S r 2 + , and the anions are P 3 − , O 2 − , S 2 − , and N 3 − .
Solution Plan For each cation-anion pair, we need to find the smallest whole number ratio of ions that results in a neutral compound. Then, we write the empirical formula with the cation listed first, and name the compound by stating the name of the cation followed by the name of the anion, with the anion name modified to end in '-ide'.
Strontium and Phosphorus
S r 2 + and P 3 − : To form a neutral compound, we need 3 S r 2 + ions for every 2 P 3 − ions. This gives us a total charge of 3 × ( + 2 ) + 2 × ( − 3 ) = + 6 − 6 = 0 . The empirical formula is S r 3 P 2 , and the name of the compound is Strontium phosphide.
Strontium and Oxygen
S r 2 + and O 2 − : To form a neutral compound, we need 1 S r 2 + ion for every 1 O 2 − ion. This gives us a total charge of + 2 − 2 = 0 . The empirical formula is S r O , and the name of the compound is Strontium oxide.
Strontium and Sulfur
S r 2 + and S 2 − : To form a neutral compound, we need 1 S r 2 + ion for every 1 S 2 − ion. This gives us a total charge of + 2 − 2 = 0 . The empirical formula is S r S , and the name of the compound is Strontium sulfide.
Strontium and Nitrogen
S r 2 + and N 3 − : To form a neutral compound, we need 3 S r 2 + ions for every 2 N 3 − ions. This gives us a total charge of 3 × ( + 2 ) + 2 × ( − 3 ) = + 6 − 6 = 0 . The empirical formula is S r 3 N 2 , and the name of the compound is Strontium nitride.
Final Answer Therefore, the empirical formulas and names of the ionic compounds are:
S r 3 P 2 , Strontium phosphide
S r O , Strontium oxide
S r S , Strontium sulfide
S r 3 N 2 , Strontium nitride
Examples
Ionic compounds are all around us! For example, sodium chloride (NaCl), or table salt, is an ionic compound that we use every day to season our food. Calcium carbonate (CaCO3), found in limestone and marble, is another common ionic compound used in construction and even as an antacid. Understanding how these compounds are formed helps us predict their properties and uses in various applications, from medicine to building materials.
