Question

Fill in the blanks in the following table: $$ \begin{array}{l|l|l|l|} \hline \text { Cation } & \text { Anion } & \text { Formula } & \text { Name } \\\ \hline \mathrm{Ni}^{2+} & \mathrm{CH}_{3} \mathrm{COO} & & \text { Sodium carbonate } \\ & & & \\ \mathrm{Ca}^{2+} & \mathrm{F}^{-} & & \\ & & \mathrm{Cu}\left(\mathrm{ClO}_{4}\right)_{2} & \\ & & & \\ & & & \\ \hline \end{array} $$

Short answer

The completed table is: $$ \begin{array}{l|l|l|l|} \hline \text { Cation } & \text { Anion } & \text { Formula } & \text { Name } \\ \hline \mathrm{Ni}^{2+} & \mathrm{CH}_{3} \mathrm{COO} & \mathrm{Ni(CH_3COO)_2} & \text { Nickel(II) acetate } \\ \mathrm{Ca}^{2+} & \mathrm{F}^{-} & \mathrm{CaF_2} & \text { Calcium fluoride } \\ \mathrm{Cu}^{2+} & \mathrm{ClO}_{4}^{-} & \mathrm{Cu(ClO_4)_2} & \text { Copper(II) perchlorate } \\ \hline \end{array} $$

Step-by-step solution

Fill in the first formula

Write the ionic formula for \(\mathrm{Ni}^{2+}\) and \(\mathrm{CH}_{3} \mathrm{COO}\). Since these have charges of +2 and -1 respectively, we need two acetate anions for every one nickel cation to make the electric charge neutral. So the ionic formula is: $$ \mathrm{Ni(CH_3COO)_2} $$

Correct the first name

The name mentioned in the first row is incorrect. Since the compound consists of Nickel and Acetate ions, the correct name should be: $$ \text{Nickel(II) acetate} $$

Fill in the second cation and name

The given formula in the second row is: $$ \mathrm{CaF_2} $$ So, we can determine that the missing cation is \(\mathrm{Ca}^{2+}\), and the name of this compound is: $$ \text{Calcium fluoride} $$

Fill in the third name

In the third row, the given formula is $$ \mathrm{Cu(ClO_4)_2} $$ It is a compound consisting of Copper and Perchlorate ions. Since Copper has a charge of +2, the correct name is: $$ \text{Copper(II) perchlorate} $$

Fill in the complete table

Now, let's fill in the completed table: $$ \begin{array}{l|l|l|l|} \hline \text { Cation } & \text { Anion } & \text { Formula } & \text { Name } \\ \hline \mathrm{Ni}^{2+} & \mathrm{CH}_{3} \mathrm{COO} & \mathrm{Ni(CH_3COO)_2} & \text { Nickel(II) acetate } \\ \mathrm{Ca}^{2+} & \mathrm{F}^{-} & \mathrm{CaF_2} & \text { Calcium fluoride } \\ \mathrm{Cu}^{2+} & \mathrm{ClO}_{4}^{-} & \mathrm{Cu(ClO_4)_2} & \text { Copper(II) perchlorate } \\ \hline \end{array} $$

Key concepts

Cations

Cations are positively charged ions. They form when an atom loses one or more electrons. Cations are usually formed by metals, as they tend to easily lose electrons during chemical reactions. The charge of a cation is indicated by a positive sign (e.g., \(\mathrm{Ni}^{2+}\), \(\mathrm{Ca}^{2+}\), and \(\mathrm{Cu}^{2+}\)).

Cations are central players in the formation of ionic compounds. When writing chemical formulas, we write the cation first followed by the anion. This order is important when naming the compound.

• Examples of cations: Sodium ion \((\mathrm{Na}^{+})\), Magnesium ion \((\mathrm{Mg}^{2+})\), Calcium ion \((\mathrm{Ca}^{2+})\).
• Common properties: They are typically metals and are often good conductors of electricity in solution.

Anions

Anions are negatively charged ions. They are formed when an atom gains one or more electrons, resulting in an excess negative charge. Nonmetals are the typical elements that become anions because they have a higher tendency to gain electrons.

The charge of an anion is shown with a negative sign, such as \(\mathrm{F}^{-}\) and \(\mathrm{ClO}_{4}^{-}\) in our exercise. Anions pair with cations to form ionic compounds, helping to balance the overall charge of the compound.

• Examples of anions: Chloride ion \((\mathrm{Cl}^{-})\), Oxide ion \((\mathrm{O}^{2-})\), Nitrate ion \((\mathrm{NO}_{3}^{-})\).
• Characteristics: Anions usually form from nonmetals, and in a solution, they help carry electrical charge.

Chemical Formulas

Chemical formulas represent the ratio and types of atoms in a compound. For ionic compounds, the chemical formula is written in a way that the total positive charge of cations equals the total negative charge of anions, making the compound electrically neutral.

For example, in \(\mathrm{Ni(CH_3COO)_2}\), the nickel \(\mathrm{Ni}^{2+}\) cation and two acetate \(\mathrm{CH_3COO}^{-}\) anions combine to neutralize the charges. The formula tells us there are two acetate ions for each nickel ion.

Steps to writing a chemical formula:

• Determine the charge of the cation and anion.
• Cross the charges to find the number of each ion needed to balance the overall charge.
• Write the cation first followed by the anion, using subscripts to indicate the number of each kind of ion.

Compound Naming

Naming ionic compounds involves combining the names of the cation and the anion. This process is crucial for ensuring that each compound has a unique and recognizable name. The name of the cation is given first, followed by the name of the anion.

For metals that can have more than one oxidation state (like copper or nickel), a Roman numeral indicates the charge of the cation in parentheses. For example, \(\text{Copper(II) perchlorate}\) gives the oxidation state +2 of the copper ion. The anion part, such as "perchlorate," comes from the name of the negative ion.

• Simplest cations (single charge): named directly after the element (e.g., Sodium for \(\mathrm{Na}^{+}\)).
• Complex cations (multiple charges): use Roman numerals (e.g., Nickel(II) for \(\mathrm{Ni}^{2+}\)).
• Anions: generally end in '-ide,' '-ate,' or '-ite,' depending on the group or the oxygen content.