Textbook Question
Draw Lewis structures that satisfy the octet rule for the following molecules and ions: d. HCN (H and N are both bonded to C),
Ch.8 - Basic Concepts of Chemical Bonding
Chapter 8, Problem 51
Which one of these statements about formal charge is true? (a) Formal charge is the same as oxidation number. (b) To draw the best Lewis structure, you should minimize formal charge. (c) Formal charge takes into account the different electronegativities of the atoms in a molecule. (d) Formal charge is most useful for ionic compounds. (e) Formal charge is used in calculating the dipole moment of a diatomic molecule.
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insert step 1> Understand the concept of formal charge: Formal charge is a theoretical charge assigned to atoms in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity.
insert step 2> Analyze statement (a): Formal charge is not the same as oxidation number. Oxidation numbers consider the electronegativity of atoms, while formal charges do not.
insert step 3> Analyze statement (b): Minimizing formal charge is a key principle in drawing the best Lewis structure, as it often leads to the most stable arrangement of atoms.
insert step 4> Analyze statement (c): Formal charge does not take into account the different electronegativities of atoms; it assumes equal sharing of electrons.
insert step 5> Analyze statement (d) and (e): Formal charge is not specifically useful for ionic compounds or in calculating dipole moments, as these concepts involve different considerations.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Formal Charge
Formal charge is a theoretical charge assigned to an atom in a molecule, calculated based on the number of valence electrons, the number of bonds, and the number of non-bonding electrons. It helps in determining the most stable Lewis structure by indicating how electrons are distributed among atoms. A formal charge of zero is often preferred for the most stable structures.
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Formal Charge
Lewis Structures
Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They are essential for visualizing molecular geometry and electron distribution. The best Lewis structure is typically the one that minimizes formal charges across the molecule, leading to greater stability.
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Oxidation Number
Oxidation number is a concept used to indicate the degree of oxidation of an atom in a compound, reflecting the number of electrons lost or gained. It differs from formal charge, as oxidation numbers consider the electronegativity of atoms and the overall charge of the molecule, while formal charge is a more localized concept focused on individual atoms in a Lewis structure.
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Related Practice
Textbook Question
Draw Lewis structures that satisfy the octet rule for the following molecules and ions: f. HOCl
Textbook Question
Write Lewis structures that satisfy the octet rule for the following molecules and ions: a. NH4+, b. C2F4 (the two C atoms are bonded to one another), c. COCl2 (the Cl atoms are bonded to C), d. HSO3− (H is bonded to one of the O atoms), e. HNC (H and C are both bonded to N), f. ClO3−.
Textbook Question
For each of the following ions of nitrogen and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms: c. NO2+.
Textbook Question
(b) With what allotrope of oxygen is it isoelectronic?