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Ch.9 - Chemical Bonding I: The Lewis Model
Chapter 9, Problem 38

How do you write a Lewis symbol for each of the following atoms or ions? a. S2– b. Mg c. Mg2+ d. P

Verified step by step guidance
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<b>Step 1:</b> Understand the concept of Lewis symbols. Lewis symbols represent the valence electrons of an atom or ion. Each dot around the symbol of the element represents one valence electron.
<b>Step 2:</b> Determine the number of valence electrons for each atom or ion. For neutral atoms, this is the same as the group number in the periodic table. For ions, adjust the number of electrons based on the charge.
<b>Step 3:</b> Write the Lewis symbol for S<sup>2–</sup>. Sulfur (S) is in group 16, so it has 6 valence electrons. As S<sup>2–</sup>, it gains 2 additional electrons, making a total of 8 valence electrons. Represent this with 8 dots around the symbol 'S'.
<b>Step 4:</b> Write the Lewis symbol for Mg. Magnesium (Mg) is in group 2, so it has 2 valence electrons. Represent this with 2 dots around the symbol 'Mg'.
<b>Step 5:</b> Write the Lewis symbol for Mg<sup>2+</sup> and P. For Mg<sup>2+</sup>, it loses 2 electrons, resulting in no valence electrons, so the symbol 'Mg' has no dots. For phosphorus (P), which is in group 15, it has 5 valence electrons, represented by 5 dots around the symbol 'P'.

Key Concepts

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

Lewis Symbols

Lewis symbols, also known as Lewis dot diagrams, represent the valence electrons of an atom or ion. Each dot corresponds to a valence electron, and the arrangement of these dots around the chemical symbol indicates how the atom can bond with others. Understanding Lewis symbols is essential for visualizing electron sharing and transfer in chemical bonding.
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Valence Electrons

Valence electrons are the outermost electrons of an atom and play a crucial role in chemical bonding. The number of valence electrons determines an atom's reactivity and the types of bonds it can form. For example, sulfur (S) has six valence electrons, while magnesium (Mg) has two, which influences how they interact with other elements.
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Ionic Charge

Ionic charge refers to the electrical charge an atom or ion carries due to the loss or gain of electrons. For instance, a magnesium ion (Mg2+) has lost two electrons, resulting in a positive charge, while a sulfide ion (S2–) has gained two electrons, leading to a negative charge. Understanding ionic charges is vital for accurately representing ions in Lewis symbols.
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