Question

Provide the formula for each of the following monoatomic cations: (a) mercurous ion (b) mercuric ion

Short answer

(a) Mercurous ion: \( \text{Hg}_2^{2+} \); (b) Mercuric ion: \( \text{Hg}^{2+} \)

Step-by-step solution

Understanding Monoatomic Cations

Monoatomic cations are ions formed from a single atom that has lost one or more electrons, resulting in a positive charge. The positive charge is denoted by a superscript after the element's symbol, indicating the number of electrons lost.

Recognize Mercury Forms

Mercury can form two types of cations known as mercurous and mercuric ions. Mercurous ions are dimers and have a +1 charge per Hg atom, while mercuric ions are single atoms with a +2 charge.

Determine the Formula for Mercurous Ion

Mercurous ions consist of two mercury atoms sharing a +2 charge over the two atoms. The chemical formula is represented as \( \text{Hg}_2^{2+} \), indicating two mercury atoms sharing a +2 charge.

Determine the Formula for Mercuric Ion

The mercuric ion is a single mercury atom that has lost two electrons, resulting in a \(+2\) charge. The chemical formula is represented as \( \text{Hg}^{2+} \).

Key concepts

Mercury Ions

Mercury, a heavy metal, can form ions when it loses electrons. There are mainly two types of mercury ions: the mercurous ion and the mercuric ion. These ions are monoatomic, meaning they consist of single mercury atoms, but they behave differently in terms of their chemistry. Understanding the behavior and formation of these ions is crucial in many chemical reactions where mercury is involved. The mercurous ion is represented as \( \text{Hg}_2^{2+} \), which might initially seem confusing because it involves a pair of mercury atoms. In this unique case, two mercury atoms bond together to form a dimer, jointly carrying a total charge of +2. Hence, each mercury atom within the dimer effectively contributes a +1 charge, resulting in the overall charge of +2 for the ion pair.
The mercuric ion is relatively simpler as it involves a single mercury atom carrying a +2 charge, represented as \( \text{Hg}^{2+} \). This occurs because the atom loses two electrons, leading to a stable configuration. Knowing these ions helps in understanding the reactivity and applications of mercury in various fields, such as chemistry and industry.

Chemical Formulas

Chemical formulas are essential in describing the composition, structure, and proportions of elements within compounds. They give you a concise way of expressing what atoms are present and their quantities. In the case of mercury ions, the formulas \( \text{Hg}_2^{2+} \) for mercurous and \( \text{Hg}^{2+} \) for mercuric provide specific information about these mercury species. The formula \( \text{Hg}_2^{2+} \) tells us there are two bonded mercury atoms carrying an overall charge of +2. Meanwhile, \( \text{Hg}^{2+} \) indicates a single mercury atom with a +2 charge. It is important to note that while these symbols may look similar, they represent different configurations of mercury ions.
Understanding chemical formulas is fundamental for anyone working with chemical equations or trying to predict the behavior of substances in reactions. These notations succinctly convey critical details that influence how compounds interact with one another, offering insights into their practical applications.

Charge Notation

Charge notation is a crucial part of understanding ions, particularly in monoatomic ions like those of mercury. This notation involves indicating the charge on an ion, which arises from the gain or loss of electrons. For a charge notation, you will see a superscript sign next to the element’s symbol: the plus sign \(+\) denotes a positive charge (loss of electrons), while the minus sign \(-\) represents a negative charge (gain of electrons). The number before the sign indicates how many electrons are lost or gained. In the case of \( \text{Hg}_2^{2+} \), the superscript "2+" shows that the ion has an overall positive charge of +2, shared between the two mercury atoms.
In the notation \( \text{Hg}^{2+} \), it indicates a loss of two electrons by a single mercury atom, resulting in a +2 charge. This type of notation helps to quickly identify the charge and the state of the ions involved, which is crucial when balancing chemical equations or predicting the reactivity of different ions in solutions. Charge notation simplifies communication in chemistry, making it easier to convey essential details about ionic species.