Textbook Question
Arrange these compounds in order of increasing magnitude of lattice energy: KCl, SrO, RbBr, CaO.
Ch.9 - Chemical Bonding I: The Lewis Model
Chapter 9, Problem 6a,d
Write the Lewis structure for each molecule or ion. a. H3COH d. O22-
Verified step by step guidance1
Step 1: Identify the total number of valence electrons for each molecule or ion. For H3COH, count the valence electrons from H (1 each), C (4), and O (6). For O22-, count the valence electrons from each O (6 each) and add 2 extra electrons for the 2- charge.
Step 2: Arrange the atoms to show how they are connected. For H3COH, place C in the center with O and H atoms around it. For O22-, place the two O atoms next to each other.
Step 3: Connect the atoms with single bonds initially. For H3COH, connect C to O and C to each H. For O22-, connect the two O atoms with a single bond.
Step 4: Distribute the remaining valence electrons to satisfy the octet rule (or duet for hydrogen). Start by completing the octets for the outer atoms first, then the central atom. Adjust bonds if necessary to ensure all atoms have a complete octet.
Step 5: Check the formal charges on each atom to ensure the most stable structure. Adjust the structure if needed to minimize formal charges, ensuring the overall charge of the ion is correct.
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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 in chemical reactions.
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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 atom's reactivity and the types of bonds it can form. In Lewis structures, counting valence electrons helps ensure that the correct number of electrons is represented in the diagram, which is vital for accurate molecular representation.
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Formal Charge
Formal charge is a concept used to determine the distribution of electrons in a molecule and to assess the stability of a Lewis structure. It is calculated by comparing the number of valence electrons in an isolated atom to the number of electrons assigned to it in the Lewis structure. A lower formal charge on atoms generally indicates a more stable structure, guiding chemists in choosing the most favorable Lewis structure for a given molecule.
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