Chapter 14: Problem 140
Which of the following are bent? (a) \(\mathrm{Br}_{3}^{+}\) (b) \(\mathrm{I}_{3}^{-}\) (c) \(\mathrm{I}_{3}+\) (d) \(\mathrm{F}_{3}^{-}\)
Short Answer
Expert verified
Only \(\mathrm{F}_{3}^{-}\) is bent.
Step by step solution
01
Determine the Molecular Geometry for \(\mathrm{Br}_{3}^{+}\)
Start by determining the number of valence electrons:- Bromine (Br) has 7 valence electrons.- For \(\mathrm{Br}_{3}^{+}\), there are 21 valence electrons with a positive charge removing 1 electron, leading to 20 valence electrons.This molecule forms a linear shape with three Br atoms and two lone pairs on the central Br atom, as removing one electron generally causes the structure to be linear.
02
Determine the Molecular Geometry for \(\mathrm{I}_{3}^{-}\)
Count the number of valence electrons:- Iodine (I) has 7 valence electrons.- For \(\mathrm{I}_{3}^{-}\), with the added electron from the negative charge, there are a total of 22 valence electrons.The structure is linear as it consists of three I atoms and has three lone pairs on the central iodine atom.
03
Determine the Molecular Geometry for \(\mathrm{I}_{3}^{+}\)
Count the number of valence electrons:- Iodine (I) has 7 valence electrons.- For \(\mathrm{I}_{3}^{+}\), the positive charge indicates that one electron is removed, giving a total of 19 valence electrons.This removal usually results in the central iodine atom having a linear geometry with other iodine atoms.
04
Determine the Molecular Geometry for \(\mathrm{F}_{3}^{-}\)
Count the valence electrons:- Fluorine (F) has 7 valence electrons.- For \(\mathrm{F}_{3}^{-}\), with the negative charge adding an extra electron, there are a total of 22 valence electrons.This molecule forms a bent shape because the central fluorine atom is affected by lone pairs that force the bond angle into a bent configuration.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with Vaia!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Valence Electrons
Valence electrons play a crucial role in determining the molecular geometry of a molecule. These are the electrons present in the outermost shell of an atom. They are primarily responsible for forming bonds with other atoms.
Understanding how to count valence electrons is the first step in predicting the shape of a molecule. For example:
For instance, a positive charge (+) usually means one less valence electron, while a negative charge (-) indicates an additional valence electron.
Understanding how to count valence electrons is the first step in predicting the shape of a molecule. For example:
- Bromine (Br) has 7 valence electrons.
- Iodine (I) also has 7 valence electrons.
- Fluorine (F) follows the same pattern with 7 valence electrons.
For instance, a positive charge (+) usually means one less valence electron, while a negative charge (-) indicates an additional valence electron.
Lone Pairs
Lone pairs are pairs of valence electrons that are not involved in bonding. They have a significant impact on the shape of molecules because they take up space and repel other electron pairs.
In molecules like I -, Br+, and F -, the presence of lone pairs on the central atom can adjust the geometry away from a straightforward shape.
- For Br+, there are two lone pairs on the central bromine atom. - The I- molecule features three lone pairs on the central iodine atom. - F - also has lone pairs, contributing to its bent structure.
The more lone pairs a molecule has, the more they push the bonded atoms into a specific configuration to minimize repulsion.
In molecules like I -, Br+, and F -, the presence of lone pairs on the central atom can adjust the geometry away from a straightforward shape.
- For Br+, there are two lone pairs on the central bromine atom. - The I- molecule features three lone pairs on the central iodine atom. - F - also has lone pairs, contributing to its bent structure.
The more lone pairs a molecule has, the more they push the bonded atoms into a specific configuration to minimize repulsion.
Linear Shape
A linear molecular shape occurs when all atoms within a molecule are arranged in a straight line. This shape usually arises when there are no lone pairs on the central atom, or they do not significantly influence the geometry due to cancellation effects.
Examples of species with a linear shape include:
Examples of species with a linear shape include:
- Br+ with two lone pairs, while three bromines align linearly due to symmetry.
- I- which also maintains a linear shape despite having lone pairs due to electrons equilibrating around the central iodine.
- A similar mechanism applies to I +.
Bent Shape
A bent molecular shape can be thought of as the outcome of repulsion between electron pairs, namely lone pairs.
In the case of molecules like F -, we observe that the central atom's geometry is influenced heavily by the lone pairs.
- F - has a bent shape because the lone pairs on the central fluorine push down the bonded atoms, resulting in a bond angle smaller than 180 degrees. - This positioning creates a V-like formation, further illustrating how electron repulsion dictates molecular geometry.
Understanding the bent shape helps in predicting the physical and chemical nature of molecules, especially how angles between bonds vary due to lone pair impacts.
In the case of molecules like F -, we observe that the central atom's geometry is influenced heavily by the lone pairs.
- F - has a bent shape because the lone pairs on the central fluorine push down the bonded atoms, resulting in a bond angle smaller than 180 degrees. - This positioning creates a V-like formation, further illustrating how electron repulsion dictates molecular geometry.
Understanding the bent shape helps in predicting the physical and chemical nature of molecules, especially how angles between bonds vary due to lone pair impacts.
