Textbook Question
The following models represent the structures of binary hydrides of second-row elements:
b. Draw an electron-dot structure for each hydride. For which hydride is there a problem in drawing the structure? Explain.
Ch.22 - The Main Group Elements
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Chapter 22, Problem 22.23b
The following pictures represent structures of the hydrides of four second-row elements:
(1)
(2)
(3)
(4)
(b) Which compound has the lowest boiling point?
Verified step by step guidance1
Identify the second-row elements in the periodic table, which are lithium (Li), beryllium (Be), boron (B), carbon (C), nitrogen (N), oxygen (O), and fluorine (F).
Recognize that hydrides are compounds formed between hydrogen and another element. For second-row elements, these hydrides are: LiH, BeH2, BH3, CH4, NH3, H2O, and HF.
Understand that boiling points are influenced by intermolecular forces such as hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
Consider that CH4 (methane) is a nonpolar molecule with only London dispersion forces, which are weaker compared to hydrogen bonding present in NH3, H2O, and HF.
Conclude that CH4, having only weak London dispersion forces and no hydrogen bonding, will have the lowest boiling point among the hydrides of second-row elements.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydride Structures
Hydrides are compounds formed between hydrogen and other elements. The structure of a hydride can significantly influence its physical properties, including boiling point. For second-row elements, the type of bonding (ionic, covalent, or metallic) and molecular geometry play crucial roles in determining the boiling point of the hydride.
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Metallic Hydrides
Intermolecular Forces
Intermolecular forces are the forces of attraction or repulsion between molecules. These forces, including hydrogen bonding, dipole-dipole interactions, and London dispersion forces, directly affect boiling points. Compounds with stronger intermolecular forces typically have higher boiling points, while those with weaker forces have lower boiling points.
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Trends in Boiling Points
Boiling points of hydrides generally exhibit trends based on molecular weight and electronegativity of the constituent elements. As you move down a group in the periodic table, boiling points tend to increase due to greater molecular weight and stronger dispersion forces. Conversely, for similar molecular weights, electronegativity differences can lead to variations in boiling points due to the strength of intermolecular forces.
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Related Practice
Textbook Question
Consider the six second- and third-row elements in groups 4A–6A of the periodic table:
Possible structures for the binary fluorides of each of these elements in its highest oxidation state are shown below.
(a) Identify the nonfluorine atom in each case, and write the molecular formula of each fluoride.
Textbook Question
The following pictures represent various silicate anions. Write the formula and charge of each anion.
Textbook Question
Select the group 4A element that best fits each of the following descriptions.
b. Is the least dense semimetal
Textbook Question
In the following pictures of binary hydrides, ivory spheres
represent H atoms or ions, and burgundy spheres represent
atoms or ions of the other element.
(1)
(2)
(3)
(4)
(a) Identify each binary hydride as ionic, covalent, or interstitial.
(b) What is the oxidation state of hydrogen in compounds (1), (2), and (3)? What is the oxidation state of the other
element?
Textbook Question
Look at the location of elements A, B, C, and D in the following periodic table:
Which hydride has the lowest boiling point?