Question

Selenium, an element required nutritionally in trace quantities, forms compounds analogous to sulfur. Name the following ions: (a) \(\mathrm{SeO}_{4}{ }^{2-}\), (b) \(\mathrm{Se}^{2-}\), (c) \(\mathrm{HSe}^{-}\), (d) \(\mathrm{HSeO}_{3}^{-}\).

Short answer

The names of the given selenium ions are: (a) selenate ion, (b) selenide ion, (c) hydrogen selenide ion, and (d) hydrogen selenite ion.

Step-by-step solution

(a) Name \(\mathrm{SeO}_{4}{ }^{2-}\)

Since selenium is analogous to sulfur and the ion is similar to sulfate ion, we can name \(\mathrm{SeO}_{4}{ }^{2-}\) as "selenate ion".

(b) Name \(\mathrm{Se}^{2-}\)

Analogous to sulfide ion, we can name the \(\mathrm{Se}^{2-}\) ion as "selenide ion".

(c) Name \(\mathrm{HSe}^{-}\)

This ion is similar to the hydrogen sulfide (HS) ion but with selenium instead of sulfur. Therefore, we can name \(\mathrm{HSe}^{-}\) as "hydrogen selenide ion".

(d) Name \(\mathrm{HSeO}_{3}^{-}\)

This ion is similar to the hydrogen sulfite (HSO3) ion but with selenium instead of sulfur. Thus, we can name \(\mathrm{HSeO}_{3}^{-}\) as "hydrogen selenite ion".

Key concepts

Selenate Ion

Selenate ion is known in chemical notation as \( \mathrm{SeO}_{4}{ }^{2-} \). It is a compound that is analogous to the sulfate ion, which is familiar in sulfur chemistry. Selenate ions are part of a family of selenium compounds that possess important chemical properties and applications.

They are formed when selenium is fully oxidized, similar to how sulfate ions are derived from sulfur. Because of the similarities in structure and properties between sulfur and selenium, selenate ions participate in analogous chemical reactions.

• In biological systems, selenate ions can be used as a source of selenium, an essential trace element for many organisms.
• These ions can be reduced in environment-based processes, often by microorganisms, contributing to selenium cycling in natural ecosystems.

Understanding the role of selenate ions in chemistry and biology helps us appreciate how essential trace elements like selenium work in nature and technology.

Selenide Ion

The selenide ion, denoted as \( \mathrm{Se}^{2-} \), is a negatively charged ion similar in function to the sulfide ion \( \mathrm{S}^{2-} \). In chemistry, selenide ions are formed when selenium gains two electrons, providing the ion with a \( 2- \) charge. This process is a common form of reduction.

Selenide compounds are known for their application in various fields, including electronics and photovoltaic technologies. Their properties stem from the unique characteristics of the selenium atom when it forms this ion.

• Selenide ions can bind with metals to form selenides, which have specific uses such as in the production of semiconductors.
• They are also sought after in the field of material science for their potential thermoelectric and optoelectronic properties.

Selenide ions, as a vital part of selenium chemistry, offer unique functional abilities that can be harnessed in industrial and technological applications.

Hydrogen Selenide Ion

The hydrogen selenide ion, with the formula \( \mathrm{HSe}^{-} \), is an interesting compound in chemistry due to its resemblance to the hydrogen sulfide ion \( \mathrm{HS}^{-} \). This ion is created by the addition of a hydrogen ion to a selenide ion.

In its gaseous form, hydrogen selenide (H_2Se) is a toxic gas that is similar to hydrogen sulfide, with a characteristic unpleasant smell. While in its ionic form, \( \mathrm{HSe}^{-} \) plays various roles in biochemical pathways where selenium is required.

• The ion can participate in redox reactions, operating within various chemical and biological contexts.
• It is also a step in the conversion and metabolism of selenium within organisms, assisting in the conservation and functional use of selenium in biological systems.

This singly negatively charged ion is pivotal in understanding the biochemistry of selenium, aiding in the essential physiological functions selenium supports.

Hydrogen Selenite Ion

Hydrogen selenite ion, represented as \( \mathrm{HSeO}_{3}^{-} \), is akin to the hydrogen sulfite ion in the sulfur series. This compound contains selenium in a lower oxidation state compared to selenate.

This ion is an important intermediate in various reactions involving selenium. In environmental chemistry, hydrogen selenite plays a vital role in selenium cycling, affecting its availability and reactivity.

• Hydrogen selenite ions can act as intermediates in biological systems, holding a transitional role in selenium transport and utilization.
• Processes involving these ions are crucial in the detoxification roles where organisms manage selenium concentrations, converting it into usable forms.

As part of the detailed selenium chemistry, the hydrogen selenite ion's role in reduction and oxidation reactions highlights the adaptability and utility of selenium in diverse chemical processes.