Question

What atom in the bicarbonate ion, \(\mathrm{HCO}_{3}^{-}\), bears the negative charge?

Short answer

The negative charge is on one of the oxygen atoms.

Step-by-step solution

Identify the Structure of the Ion

The bicarbonate ion \(\mathrm{HCO}_{3}^{-}\) is composed of one hydrogen (H) atom, one carbon (C) atom, and three oxygen (O) atoms. Understanding the arrangement of these atoms is crucial.

Determine Possible Charge Locations

In \(\mathrm{HCO}_{3}^{-}\), the negative charge can be located on one of the oxygen atoms or possibly shared across different atoms. We know the common valences: H is typically +1, C usually forms four covalent bonds and is often neutral when satisfied, and O is typically -2.

Apply the Octet Rule

For atoms to be stable, they often follow the octet rule, which means having eight electrons in their outer shell. Oxygen often takes this form by having a double bond, single bond, or carrying a negative charge to satisfy this condition.

Analyze the Charge Balance

Considering the octet rule and typical valences, in \(\mathrm{HCO}_{3}^{-}\), the carbon atom is bonded to the oxygen atoms and one hydrogen, forming a neutral core. Thus, the leftover negative charge is most likely on one of the oxygen atoms, typically the one that is singly bonded (with a single bond rather than a double bond), to complete an outer shell with eight electrons.

Conclusion on the Charge Location

Since oxygen bears negative charges when singly bonded (as this completes its octet), the negative charge in \(\mathrm{HCO}_{3}^{-}\) is located on the oxygen atom with a single bond to carbon, carrying a total of seven valence electrons including the negative charge.

Key concepts

Atomic Structure

Atoms serve as the fundamental building blocks of matter. Each atom consists of a nucleus at its core, comprised of protons and neutrons, surrounded by a cloud of electrons. In an ion such as the bicarbonate ion (\(\mathrm{HCO}_3^-\)), atomic structure becomes crucial for understanding its behavior.
An analysis of this ion's atomic structure reveals that it includes one hydrogen (H), one carbon (C), and three oxygen (O) atoms. Understanding the positions and bonding between these atoms allows us to comprehend how the ion interacts and where charges may reside.
Typically, the structure ensures maximum stability, often highlighting the significance of chemical bonds and interactions between the electrons in these atoms. The bonds formed and the electron arrangement influence the resultant charge distribution across the ion.

Negative Charge Location

Identifying the location of a negative charge in a molecule like the bicarbonate ion involves understanding where extra electrons can be accommodated. This negative charge is crucial because it affects the ion's chemical reactivity and interactions.
In the bicarbonate ion \(\mathrm{HCO}_3^-\), the oxygen atoms are the primary contenders to bear this charge. Due to their higher electronegativity, oxygen atoms are more inclined to attract and retain additional electrons compared to hydrogen or carbon atoms.

• The negative charge typically resides on an oxygen atom that forms a single bond with carbon, resulting in a scenario where this oxygen has extra electrons.
• This oxygen atom, carrying the negative charge, is more likely to have an incomplete octet before acquiring extra electrons.

Thus, recognizing the electrons' distribution helps pinpoint the negative charge's precise location in molecular structures.

Octet Rule

The octet rule is an essential principle for understanding molecular structures, particularly within chemistry. It states that atoms tend to have eight electrons in their outer shell, achieving a stable configuration reminiscent of noble gases.
For the bicarbonate ion, this rule helps determine how atoms share or transfer electrons to complete their octets.

• Oxygen, striving for an octet, might achieve this through double bonding or through holding a negative charge when forming ions like \(\mathrm{HCO}_3^-\).
• Carbon, generally forming four covalent bonds, completes its octet by bonding with oxygen and hydrogen atoms.

This rule guides the stability and formation of the ion, influencing which atoms are more likely to carry additional charges based on their bond types and resultant electron distribution.

Valence Electrons

Valence electrons are those electrons present in the outermost shell of an atom. They are instrumental in bond formation, dictating an atom's chemical properties and interactions.
In the bicarbonate ion, each constituent element brings its valence electrons into play:

• Hydrogen has one valence electron, participating in bonding with carbon.
• Carbon, with four valence electrons, forms bonds to fulfill its octet, effectively varying between differerent states of oxidation.
• Oxygen, possessing six valence electrons, participates in either single or double bonds and may also carry a negative charge.

Figuring out how these electrons are shared or transferred among the atoms helps determine the ionic and molecular structure, properties, and behaviors, such as assigning locations for any extra charges like in \(\mathrm{HCO}_3^-\).