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Ch.9 - Chemical Bonding I: The Lewis Model
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831Not the one you use?Change textbook
All textbooksTro 4th EditionCh.9 - Chemical Bonding I: The Lewis ModelProblem 61a,b,c
Chapter 9, Problem 61a,b,c

Write the Lewis structure for each molecule or ion. a. N2H2 b. N2H4 c. C2H2

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Step 1: Determine the total number of valence electrons for each molecule or ion. For N2H2, each nitrogen (N) has 5 valence electrons and each hydrogen (H) has 1 valence electron. Calculate the total valence electrons for N2H2. Repeat this process for N2H4 and C2H2.
Step 2: Arrange the atoms to show how they are connected. For N2H2, the two nitrogen atoms are connected by a double bond, and each nitrogen is bonded to one hydrogen atom. For N2H4, the two nitrogen atoms are connected by a single bond, and each nitrogen is bonded to two hydrogen atoms. For C2H2, the two carbon atoms are connected by a triple bond, and each carbon is bonded to one hydrogen atom.
Step 3: Distribute the remaining valence electrons to satisfy the octet rule for each atom, starting with the outer atoms. Ensure that each hydrogen atom has 2 electrons (a full shell) and each nitrogen and carbon atom has 8 electrons (an octet).
Step 4: Check the formal charges on each atom to ensure the most stable structure. The formal charge is calculated as: Formal Charge = (Valence electrons) - (Non-bonding electrons) - 0.5*(Bonding electrons). Adjust the structure if necessary to minimize formal charges.
Step 5: Draw the final Lewis structure for each molecule or ion, ensuring that all atoms have the appropriate number of electrons and that the structure is as stable as possible.

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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 use dots to represent valence electrons and lines to represent bonds between atoms. Understanding how to draw Lewis structures is essential for visualizing molecular geometry and predicting the behavior of molecules.
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Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining how atoms bond with each other. The number of valence electrons influences the molecule's reactivity and stability. For example, nitrogen has five valence electrons, which play a key role in forming bonds in nitrogen-containing compounds like N2H2 and N2H4.
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Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is influenced by the number of bonds and lone pairs around the central atom, which can affect the molecule's physical and chemical properties. Understanding molecular geometry helps in predicting the shape and reactivity of molecules like C2H2.
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