Chapter 4: Problem 68
Based on formal charge considerations, which of the following would likely be the correct arrangement of atoms in hypochlorous acid: HOCl or OCIH?
Short Answer
Expert verified
The correct arrangement of atoms in hypochlorous acid, based on formal charge considerations, is HOCl since it results in a more stable molecule with formal charges of zero on all atoms.
Step by step solution
01
Understanding the Concept of Formal Charge
Formal charge is a concept used to estimate the way electric charge is distributed in a molecule. It is calculated using the formula: Formal Charge = (Valence electrons of an atom) - (Non-bonding electrons) - (1/2 * Bonding electrons). A structure is generally more stable when formal charges are closer to zero.
02
Drawing Lewis Structures for HOCl and OCIH
To determine the correct arrangement of atoms, begin by drawing Lewis structures for both HOCl and OCIH. In both structures, place oxygen (O) in the center because it is less electronegative than chlorine (Cl) and more electronegative than hydrogen (H). Connect hydrogen (H) to oxygen (O) with a single bond in HOCl and connect hydrogen (H) with chlorine (Cl) in OCIH. Then, connect chlorine (Cl) and oxygen (O) with a single bond.
03
Calculating Formal Charges for HOCl
Calculate the formal charges for the atoms in HOCl. For oxygen in HOCl, the formal charge is (6 valence electrons) - (4 non-bonding electrons) - (1/2 * 4 bonding electrons) = 0. For chlorine, (7 valence electrons) - (6 non-bonding electrons) - (1/2 * 2 bonding electrons) = 0. For hydrogen, (1 valence electron) - (0 non-bonding electrons) - (1/2 * 2 bonding electrons) = 0. All atoms have a formal charge of 0, suggesting stability.
04
Calculating Formal Charges for OCIH
Calculate the formal charges for the atoms in OCIH. For oxygen (6 valence electrons) - (6 non-bonding electrons) - (1/2 * 2 bonding electrons) = -1. For chlorine (7 valence electrons) - (2 non-bonding electrons) - (1/2 * 6 bonding electrons) = +1. For hydrogen, (1 valence electron) - (0 non-bonding electrons) - (1/2 * 2 bonding electrons) = 0. Oxygen has a formal charge of -1 and chlorine has a formal charge of +1, indicating a less stable arrangement compared to HOCl.
05
Analyzing the Most Favorable Arrangement
Based on the calculated formal charges, the arrangement with the charges closest to zero is more stable and likely the correct arrangement. Since HOCl has formal charges of zero on all atoms, and OCIH has formal charges of -1 and +1, the HOCl arrangement is favored.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Lewis Structures
When studying chemical molecules, Lewis structures are commonly used as a visual representation to depict the arrangement of atoms within a molecule and the distribution of electrons amongst these atoms. Named after the chemist Gilbert N. Lewis, they serve as a bridge between the elements' atomic structure and their chemical bonding.
Lewis structures allow us to understand how atoms bond in molecules by demonstrating possible connection patterns based on shared electron pairs, represented by lines (or dashes), and lone pairs, shown as dots. This exercise involves drawing and comparing the Lewis structures for HOCl and OCIH to determine the more stable molecule. The stability of the molecule can often be predicted by the absence of formal charges on individual atoms, signaling a preferred electron distribution. By mastering the drawing of Lewis structures, students can better predict molecular geometry, reactivity, and polarity—a fundamental skill in chemistry.
Lewis structures allow us to understand how atoms bond in molecules by demonstrating possible connection patterns based on shared electron pairs, represented by lines (or dashes), and lone pairs, shown as dots. This exercise involves drawing and comparing the Lewis structures for HOCl and OCIH to determine the more stable molecule. The stability of the molecule can often be predicted by the absence of formal charges on individual atoms, signaling a preferred electron distribution. By mastering the drawing of Lewis structures, students can better predict molecular geometry, reactivity, and polarity—a fundamental skill in chemistry.
Molecular Stability
Molecular stability is inherent to the formation and structure of compounds. It refers to the tendency of a molecule to maintain its integrity and resist breaking apart under normal conditions. A critical factor influencing this stability is the distribution of formal charges throughout the molecule.
In the context of the exercise, you can see how formal charge calculations lead to the determination of a more stable molecular arrangement. Molecules where formal charges are minimized or neutral are generally considered to be more stable. This is because a balanced charge distribution enables the electrons to reside more comfortably around an atom, aligning with its electronegativity and reducing the likelihood of electron repulsion or uneven distribution that can lead to reactivity. By quantifying the formal charges in HOCl and OCIH and observing that HOCl has a zero formal charge, the conclusion is those involved in this more favorable arrangement.
In the context of the exercise, you can see how formal charge calculations lead to the determination of a more stable molecular arrangement. Molecules where formal charges are minimized or neutral are generally considered to be more stable. This is because a balanced charge distribution enables the electrons to reside more comfortably around an atom, aligning with its electronegativity and reducing the likelihood of electron repulsion or uneven distribution that can lead to reactivity. By quantifying the formal charges in HOCl and OCIH and observing that HOCl has a zero formal charge, the conclusion is those involved in this more favorable arrangement.
Electron Distribution in Molecules
The electron distribution within a molecule profoundly affects its properties and is pivotal in understanding chemical bonding. Electrons can either be part of bonding pairs, which hold atoms together, or non-bonding pairs, which are not directly involved in bonding but still influence the shape and charge distribution of the molecule.
The step-by-step solution to our exercise emphasizes the significance of electron distribution in calculating the formal charges of different atoms within a molecule. The goal is to achieve as neutral a charge as possible on each atom, correlating to a more energetically favorable and less reactive arrangement. Calculating the formal charge incorporates both non-bonding electrons and the shared bonding electrons, revealing how electrons are distributed around an atom relative to its expected number of valence electrons. Such insights are not only essential for anticipating molecular stability but also for predicting bonding patterns and molecular shapes.
The step-by-step solution to our exercise emphasizes the significance of electron distribution in calculating the formal charges of different atoms within a molecule. The goal is to achieve as neutral a charge as possible on each atom, correlating to a more energetically favorable and less reactive arrangement. Calculating the formal charge incorporates both non-bonding electrons and the shared bonding electrons, revealing how electrons are distributed around an atom relative to its expected number of valence electrons. Such insights are not only essential for anticipating molecular stability but also for predicting bonding patterns and molecular shapes.