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Ch.10 - Chemical Bonding II: Molecular Shapes & Valence Bond Theory
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831Not the one you use?Change textbook
All textbooksTro 4th EditionCh.10 - Chemical Bonding II: Molecular Shapes & Valence Bond TheoryProblem 42c
Chapter 10, Problem 42c

Determine the molecular geometry about each interior atom and sketch each molecule. c. N2H4 (skeletal structure H2NNH2)

Verified step by step guidance
1
Step 1: Identify the central atoms in the molecule.
In N2H4, the central atoms are the two nitrogen atoms, as the skeletal structure is H2NNH2.
Step 2: Determine the number of electron groups around each nitrogen atom.
Each nitrogen atom in N2H4 is bonded to two hydrogen atoms and one nitrogen atom, making a total of three bonding pairs and one lone pair of electrons.
Step 3: Use VSEPR theory to predict the molecular geometry around each nitrogen atom.
With three bonding pairs and one lone pair, the electron geometry is tetrahedral, but the molecular geometry is trigonal pyramidal.
Step 4: Sketch the molecule based on the determined geometry.
Draw each nitrogen atom with a trigonal pyramidal shape, showing the hydrogen atoms and the lone pair on each nitrogen.
Step 5: Verify the molecular geometry by considering the bond angles.
In a trigonal pyramidal geometry, the bond angles are slightly less than 109.5° due to the presence of the lone pair, which repels the bonding pairs.

Key Concepts

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

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) Theory is a model used to predict the geometry of individual molecules based on the repulsion between electron pairs in the valence shell of the central atom. According to this theory, electron pairs will arrange themselves as far apart as possible to minimize repulsion, leading to specific molecular shapes.
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Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals that can accommodate bonding. In the case of N2H4, the nitrogen atoms undergo sp3 hybridization, which allows for the formation of four equivalent bonds, resulting in a tetrahedral arrangement around each nitrogen atom.
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Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. For N2H4, the molecular geometry around each nitrogen atom is approximately tetrahedral due to the presence of two bonded hydrogen atoms and one lone pair, influencing the overall shape of the molecule.
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