Question

Give the names and charges of the cation and anion in each of the following compounds: (a) \(\mathrm{CaO}\), (b) \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{KClO}_{4},(\mathrm{~d}) \mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2},(\mathrm{e}) \mathrm{Cr}(\mathrm{OH})_{3}\)

Short answer

In (a) CaO, the cation is Calcium with a charge of +2 (\(\mathrm{Ca}^{2+}\)), and the anion is Oxygen with a charge of -2 (\(\mathrm{O}^{2-}\)). In (b) \(\mathrm{Na}_{2}\mathrm{SO}_{4}\), the cation is Sodium with a charge of +1 (\(\mathrm{Na}^{+}\)), and the anion is Sulfate with a charge of -2 (\(\mathrm{SO}_4^{2-}\)). In (c) \(\mathrm{KClO}_{4}\), the cation is Potassium with a charge of +1 (\(\mathrm{K}^{+}\)), and the anion is Perchlorate with a charge of -1 (\(\mathrm{ClO}_4^{-}\)). In (d) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\), the cation is Iron with a charge of +2 (\(\mathrm{Fe}^{2+}\)), and the anion is Nitrate with a charge of -1 (\(\mathrm{NO}_3^{-}\)). In (e) \(\mathrm{Cr}(\mathrm{OH})_{3}\), the cation is Chromium with a charge of +3 (\(\mathrm{Cr}^{3+}\)), and the anion is Hydroxide with a charge of -1 (\(\mathrm{OH}^{-}\)).

Step-by-step solution

Identify cation and anion in CaO

Here, the given compound is \(\mathrm{CaO}\). The elements present are Calcium (Ca) and Oxygen (O). Calcium is in Group 2 of the periodic table, and it forms a cation with a charge of +2. Oxygen is in Group 16 of the periodic table, and it forms an anion with a charge of -2. #Answer for (a)

Cation and Anion with their charges

In CaO, the cation is Calcium with a charge of +2 (\(\mathrm{Ca}^{2+}\)), and the anion is Oxygen with a charge of -2 (\(\mathrm{O}^{2-}\)). #b)

Identify cation and anion in \(\mathrm{Na}_{2}\mathrm{SO}_{4}\)

Here, the given compound is \(\mathrm{Na}_{2}\mathrm{SO}_{4}\). The elements are Sodium (Na) and Sulfate (SO₄). Sodium is in Group 1 of the periodic table, and it forms a cation with a charge of +1. Sulfate (SO₄) is a polyatomic anion with a charge of -2. #Answer for (b)

Cation and Anion with their charges

In \(\mathrm{Na}_{2}\mathrm{SO}_{4}\), the cation is Sodium with a charge of +1 (\(\mathrm{Na}^{+}\)), and the anion is Sulfate with a charge of -2 (\(\mathrm{SO}_4^{2-}\)). #c)

Identify cation and anion in \(\mathrm{KClO}_{4}\)

Here, the given compound is \(\mathrm{KClO}_{4}\). The elements are Potassium (K) and Perchlorate (ClO₄). Potassium is in Group 1 of the periodic table, and it forms a cation with a charge of +1. Perchlorate (ClO₄) is a polyatomic anion with a charge of -1. #Answer for (c)

Cation and Anion with their charges

In \(\mathrm{KClO}_{4}\), the cation is Potassium with a charge of +1 (\(\mathrm{K}^{+}\)), and the anion is Perchlorate with a charge of -1 (\(\mathrm{ClO}_4^{-}\)). #d)

Identify cation and anion in \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\)

Here, the given compound is \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\). The elements are Iron (Fe) and Nitrate (NO₃). Iron forms a cation with a charge of +2 since there are two nitrates, and by balancing the charges, we get the charge on Iron. Nitrate (NO₃) is a polyatomic anion with a charge of -1. #Answer for (d)

Cation and Anion with their charges

In \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\), the cation is Iron with a charge of +2 (\(\mathrm{Fe}^{2+}\)), and the anion is Nitrate with a charge of -1 (\(\mathrm{NO}_3^{-}\)). #e)

Identify cation and anion in \(\mathrm{Cr}(\mathrm{OH})_{3}\)

Here, the given compound is \(\mathrm{Cr}(\mathrm{OH})_{3}\). The elements are Chromium (Cr) and Hydroxide (OH). Chromium forms a cation with a charge of +3 since there are three hydroxides, and by balancing the charges, we get the charge on Chromium. Hydroxide (OH) is a polyatomic anion with a charge of -1. #Answer for (e)

Cation and Anion with their charges

In \(\mathrm{Cr}(\mathrm{OH})_{3}\), the cation is Chromium with a charge of +3 (\(\mathrm{Cr}^{3+}\)), and the anion is Hydroxide with a charge of -1 (\(\mathrm{OH}^{-}\)).

Key concepts

Cation and Anion Identification

When identifying cations and anions in chemical compounds, it is essential to recognize the roles they play. Cations are positively charged ions, resulting from an atom or molecule that has lost one or more electrons. Conversely, anions are negatively charged ions formed when an atom or molecule gains electrons.

Let's look at some examples:

• In CaO, Calcium (Ca) is the cation with a +2 charge because it has lost two electrons, whereas Oxygen (O) is the anion with a -2 charge as it has gained two electrons.
• In Na₂SO₄, Sodium (Na) acts as the cation with a +1 charge, while Sulfate (SO₄) acts as the anion with a -2 charge, highlighting the presence of both simple and polyatomic ions in compounds.

Understanding the charges on cations and anions is crucial for predicting ionic compound formations and properties.

Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms bonded together, carrying a net charge. Importantly, they act as single units in chemical reactions. Unlike monatomic ions that consist of a single atom, polyatomic ions have more complex structures but function similarly when forming ionic compounds.

Examples can help illustrate this concept:

• Sulfate (SO₄) in Na₂SO₄ is a polyatomic anion with a -2 charge. It joins sodium ions to form the ionic compound sodium sulfate.
• Perchlorate (ClO₄) in KClO₄ is also a polyatomic anion, carrying a -1 charge and pairing with potassium ions.

Grasping the behavior of these given polyatomic ions is essential for comprehending the intricacies of complex compounds.

Periodic Table Groups

The periodic table groups are powerful tools for predicting the charges of ions. Elements in the same group have similar valence electron configurations, which influence their tendency to lose or gain electrons, and thus their ionic charges.

Consider these examples:

• Group 1 elements like Sodium (Na) and Potassium (K) typically form cations with a +1 charge, as they lose one electron to achieve a stable electron configuration.
• Group 2 elements like Calcium (Ca) form cations with a +2 charge by losing two electrons.

Likewise, nonmetals like Oxygen, which belongs to Group 16, tend to gain electrons, forming anions with a -2 charge. Therefore, knowing the periodic table groups can guide you in predicting the charges and forming ions.

Ionic Charge Balancing

Ionic charge balancing is key to forming stable ionic compounds. For a compound to be electrically neutral, the total positive and negative charges must balance out. This balance is achieved by ensuring the cation and anion charges add up to zero.

Here’s how it works with some compounds:

• In CaO, Calcium ( Ca^{2+}) and Oxygen ( O^{2-}) balance each other, making the compound neutral.
• In Fe(NO₃)₂, the iron cation ( Fe^{2+}) is balanced by two nitrate anions ( NO₃^{-}), resulting in a neutral compound.

The ability to balance ionic charges is fundamental in predicting and writing the chemical formulas of ionic compounds accurately.