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Ch.7 - Covalent Bonding and Electron-Dot Structures
Chapter 7, Problem 72

Identify the third-row elements, X, that form the following ions. (a) Lewis dot structure showing fluorine atoms bonded to element X in a neutral compound.

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Identify the element X in the Lewis dot structure. The structure shows X bonded to four fluorine (F) atoms.
Determine the number of valence electrons for fluorine (F). Fluorine has 7 valence electrons.
Calculate the total number of valence electrons in the compound. Each fluorine contributes 7 electrons, and there are 4 fluorines, so 4 * 7 = 28 electrons from fluorine.
Consider the octet rule for the central atom X. Since X is bonded to four fluorines, it must share 4 electrons with each fluorine, totaling 4 * 1 = 4 electrons from X.
Identify the third-row element that can have 4 valence electrons available for bonding and can form a stable compound with 4 fluorine atoms. The element is silicon (Si).

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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. Understanding how to draw and interpret Lewis structures is essential for predicting molecular geometry and reactivity.
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Ionic and Covalent Bonds

Ionic bonds form when electrons are transferred from one atom to another, resulting in charged ions that attract each other. Covalent bonds, on the other hand, involve the sharing of electrons between atoms. Recognizing whether an element forms ionic or covalent bonds helps in identifying the types of ions that can be formed by third-row elements.
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Group Trends in the Periodic Table

Elements in the same group of the periodic table exhibit similar chemical properties due to their similar valence electron configurations. For third-row elements, understanding their position in the periodic table helps predict their ability to form specific ions, such as cations or anions, based on their electronegativity and ionization energy.
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