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Ch.9 - Molecular Geometry and Bonding Theories
Chapter 9, Problem 48

How would you expect the extent of overlap of the bonding atomic orbitals to vary in the series IF, ICl, IBr, and I2? Explain your answer.

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Identify the concept of atomic orbital overlap: The extent of overlap between atomic orbitals is crucial for bond strength. Greater overlap generally leads to stronger bonds.
Consider the size of the halogen atoms: As you move down the halogen group in the periodic table (F, Cl, Br, I), the atomic size increases.
Analyze the effect of atomic size on overlap: Larger atoms have more diffuse orbitals, which can lead to less effective overlap compared to smaller atoms.
Compare the pairs: In the series IF, ICl, IBr, and I2, the overlap is expected to be greatest in IF and least in I2, as fluorine is the smallest atom and iodine is the largest.
Conclude with the trend: The extent of overlap decreases as the size of the halogen atom bonded to iodine increases, leading to weaker bonds in the order IF > ICl > IBr > I2.

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Key Concepts

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

Atomic Orbitals

Atomic orbitals are regions in an atom where there is a high probability of finding electrons. They come in different shapes (s, p, d, f) and sizes, which influence how atoms bond with each other. The overlap of atomic orbitals between two atoms is crucial for the formation of covalent bonds, as greater overlap typically leads to stronger bonds.
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Bonding and Overlap

The extent of overlap between atomic orbitals is a key factor in determining the strength and stability of a covalent bond. When two atomic orbitals overlap significantly, they can share electrons more effectively, resulting in a stronger bond. In the context of the given compounds, the size and electronegativity of the atoms involved will affect how well their orbitals can overlap.
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Electronegativity and Bonding Characteristics

Electronegativity is a measure of an atom's ability to attract and hold onto electrons. In the series IF, ICl, IBr, and I2, the differences in electronegativity between iodine and the other halogens (F, Cl, Br) will influence the nature of the bonds formed. Higher electronegativity differences can lead to more polar bonds, affecting the overlap of bonding orbitals and the overall bond strength.
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