Ch.9 - Molecular Geometry and Bonding Theories

Problem 113a

Chapter 9, Problem 113a

Methyl isocyanate, CH₃NCO, was made infamous in 1984 when an accidental leakage of this compound from a storage tank in Bhopal, India, resulted in the deaths of about 3800 people and severe and lasting injury to many thousands more. (a) Draw a Lewis structure for methyl isocyanate.

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Identify the total number of valence electrons in the molecule. Carbon (C) has 4, hydrogen (H) has 1, nitrogen (N) has 5, and oxygen (O) has 6. Calculate the total valence electrons for CH3NCO.

Determine the central atom. In this case, carbon (C) is often the central atom in organic molecules. Arrange the atoms in a reasonable structure: CH3 connected to NCO.

Draw single bonds between the central carbon and the surrounding atoms: C-H, C-N, and N-C-O. This uses up some of the valence electrons.

Distribute the remaining valence electrons to satisfy the octet rule for each atom, starting with the most electronegative atoms (O and N).

Adjust the structure to minimize formal charges, possibly by creating double or triple bonds, especially between C, N, and O, to ensure all atoms have a complete octet.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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 help visualize the arrangement of electrons and the connectivity of atoms, allowing chemists to predict molecular geometry and reactivity. In drawing a Lewis structure, one must account for the total number of valence electrons and ensure that each atom achieves a stable electron configuration, typically resembling that of noble gases.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining how an atom bonds with others. The number of valence electrons influences an atom's reactivity and the types of bonds it can form. For example, carbon has four valence electrons, allowing it to form four covalent bonds, while nitrogen has five, enabling it to form three bonds and hold a lone pair.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is determined by the number of bonding pairs and lone pairs of electrons around the central atom, which affects the molecule's shape and properties. Understanding molecular geometry is essential for predicting the behavior of molecules in chemical reactions and their interactions with other substances.

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Related Practice

Textbook Question

Sulfur tetrafluoride (SF₄) reacts slowly with O₂ to form sulfur tetrafluoride monoxide (OSF₄) according to the following unbalanced reaction: SF₄(g) + O₂(g) → OSF₄(g) The O atom and the four F atoms in OSF₄ are bonded to a central S atom. (b) Write a Lewis structure of OSF₄ in which the formal charges of all atoms are zero.

Textbook Question

Sulfur tetrafluoride (SF₄) reacts slowly with O₂ to form sulfur tetrafluoride monoxide (OSF₄) according to the following unbalanced reaction: SF₄(g) + O₂(g) → OSF₄(g) The O atom and the four F atoms in OSF₄ are bonded to a central S atom. (c) Use average bond enthalpies (Table 8.3) to estimate the enthalpy of the reaction. Is it endothermic or exothermic?

Textbook Question

Sulfur tetrafluoride 1SF42 reacts slowly with O2 to form sulfur

tetrafluoride monoxide 1OSF42 according to the following

unbalanced reaction:

SF41g2 + O21g2¡OSF41g2

The O atom and the four F atoms in OSF4 are bonded to a

central S atom.

(e) For each of the molecules you drew in part (d), state how many

fluorines are equatorial and how many are axial.

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Methyl isocyanate, CH3NCO, was made infamous in 1984 when an accidental leakage of this compound from a storage tank in Bhopal, India, resulted in the deaths of about 3800 people and severe and lasting injury to many thousands more. (a) Draw a Lewis structure for methyl isocyanate.

Verified video answer for a similar problem:

Key Concepts

Lewis Structures

Valence Electrons

Molecular Geometry

Methyl isocyanate, CH₃NCO, was made infamous in 1984 when an accidental leakage of this compound from a storage tank in Bhopal, India, resulted in the deaths of about 3800 people and severe and lasting injury to many thousands more. (a) Draw a Lewis structure for methyl isocyanate.