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Ch.8 - Basic Concepts of Chemical Bonding
Chapter 8, Problem 36e

Use Lewis symbols and Lewis structures to diagram the formation of PF3 from P and F atoms, showing valence-shell electrons. e. How many bonding pairs of electrons are in the PF3 molecule?

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Draw the Lewis symbols for phosphorus (P) and fluorine (F). Phosphorus has 5 valence electrons, and fluorine has 7 valence electrons.
Arrange the P atom in the center and surround it with three F atoms, as phosphorus is less electronegative and can form multiple bonds.
Share one electron from the P atom with one electron from each F atom to form a single bond, creating three P-F bonds.
Each P-F bond represents a bonding pair of electrons. Count the number of bonding pairs formed.
Verify that each atom achieves a stable electron configuration: P should have 8 electrons around it, and each F should have 8 electrons, including the shared electrons in the bonds.

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Key Concepts

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

Lewis Symbols

Lewis symbols represent the valence electrons of an atom as dots surrounding the element's symbol. Each dot corresponds to a valence electron, allowing for a visual representation of how atoms bond. In the case of phosphorus (P) and fluorine (F), understanding their Lewis symbols is essential for predicting how they will interact to form PF3.
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Lewis Structures

Lewis structures are diagrams that depict the arrangement of atoms and the distribution of valence electrons in a molecule. They illustrate bonding pairs (shared electrons) and lone pairs (non-bonding electrons). For PF3, drawing the Lewis structure helps visualize how phosphorus forms three single bonds with three fluorine atoms, clarifying the molecular geometry and electron sharing.
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Bonding Pairs of Electrons

Bonding pairs of electrons are pairs of electrons that are shared between two atoms, forming a covalent bond. In PF3, each P-F bond consists of one bonding pair, leading to a total of three bonding pairs in the molecule. Understanding the concept of bonding pairs is crucial for determining the molecular structure and properties of PF3.
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