Question

Name the following compound: \(\mathrm{Cu}\left(\mathrm{ClO}_4\right)_2\). A. copper(I) chlorate B. copper(II) perchlorite C. copper(1I) chlorate D. copper(II) perchlorate

Short answer

D. copper(II) perchlorate

Step-by-step solution

Identify the central metal ion

The central metal ion in \(\text{Cu(ClO}_4)_2\) is copper (Cu).

Determine the oxidation state of copper

Each \( \text{ClO}_4^- \) ion has a \-1\ charge. Since there are two of them, they contribute a total of \-2\ charge. For the overall compound to be neutral, copper must have a \(+2\) oxidation state to balance the \-2\ charge from the two \( \text{ClO}_4^- \) ions.

Identify the polyatomic ion

The polyatomic ion present is \( \text{ClO}_4^- \), which is called perchlorate.

Name the compound

Combine the name of the metal ion (with its oxidation state) and the polyatomic ion. The correct name for the compound \( \text{Cu(ClO}_4)_2 \) is copper(II) perchlorate.

Key concepts

Oxidation States

Understanding oxidation states is crucial when naming inorganic compounds. The oxidation state, also called oxidation number, represents the charge that an atom would have if all bonds to atoms of different elements were fully ionic. In the case of the compound \(\text{Cu(ClO}_4)_2\), copper is the central metal ion. To find its oxidation state, we need to look at the charges of the other components. Each perchlorate ion (\(\text{ClO}_4^-\)) has a \-1\ charge. With two perchlorate ions, the total negative charge is \-2\. For the compound to be neutral, copper must have a \(+2\) charge to balance out the \-2\ from the perchlorate ions. Therefore, we determine that copper is in the \(+2\) oxidation state in this compound.

Polyatomic Ions

Polyatomic ions are ions with two or more atoms bonded together that carry a charge. In \(\text{Cu(ClO}_4)_2\), the polyatomic ion is perchlorate (\(\text{ClO}_4^-\)). Recognizing common polyatomic ions like perchlorate is essential for naming compounds correctly. The name of a polyatomic ion does not change no matter what it is bonded to. In this example, \(\text{ClO}_4^-\) is always perchlorate. The formula tells us there are two perchlorate ions present. Identifying polyatomic ions that's part of a compound makes naming it much simpler. The ion retains its name, and we just need to account for the central metal's oxidation state when putting it all together.

Transition Metals

Transition metals can have multiple oxidation states, which is why we must specify the oxidation state in the compound's name. For example, copper can exist in multiple oxidation states, commonly \(+1\) and \(+2\). In \(\text{Cu(ClO}_4)_2\), since copper has two \(+2\) states, it is important to indicate that in the name. This is done using Roman numerals, resulting in 'copper(II)' for \(Cu^{2+}\). Highlighting the right oxidation state ensures clear communication and avoids confusion. It's a key detail in nomenclature, particularly for compounds involving transition metals with various possible charges.