Write the Lewis structure for each molecule. a. PH 3 b. SCl 2 c. HI

Hello everyone today. We are being asked to draw a reasonable lewis dot structure for phosphorous tri chloride or PCL three. So the first thing I wanna make notice of how many of each atom that we have. So we know that we have one phosphorus atom and phosphorus is in the fifth group on the periodic table and therefore has five valence electrons. This gives us a total of five valence electrons to work with tri chloride means we have three chlorides chlorine atoms. And because chlorine is in the seventh group on the periodic table, it has seven valence electrons giving us 21 valence electrons. And in total we have 26 valence electrons to work with. Next we must make note of the least electro negative adam that goes in the center so it goes in the center of the rest of the atoms. And according to the periodic table trend, the electro negativity increases as we go upward and to the right. So phosphorus would be considered least electro negative and therefore would be in the center surrounded by three different chlorine atoms drawn as such. We have now connected these four atoms with three bond lines and each bond line has two electrons. So we went from 26 valence electrons - to just 20 next we must make sure that we fulfill the octet rule and also the valence electron rule. So chlorine is in the seventh group. So it has seven valence electrons. And now we must draw six individual electrons around each chlorine atom to fulfill that rule. And so now each chlorine atom has eight total electrons but seven valence electrons. And so we've used 18 of our electrons and we only have two valence electrons. Left phosphorus is on the fifth group on the periodic table, as dated before, it has five valence electrons. So since it has three already directly attached to it, we must add the two remaining electrons. We're left with zero valence electrons and we have our structure for phosphorous tri chloride. I hope this helped. And until next time.

Ch.10 - Chemical Bonding I: The Lewis Model

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Ch.10 - Chemical Bonding I: The Lewis Model

Problem 55a,b,c

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Chapter 10, Problem 55a,b,c

Write the Lewis structure for each molecule. a. PH₃ b. SCl₂ c. HI

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Determine the total number of valence electrons in the molecule. Phosphorus (P) has 5 valence electrons, and each hydrogen (H) has 1 valence electron. Since there are three hydrogen atoms, the total number of valence electrons is 5 + 3(1) = 8.

Place the least electronegative atom in the center. In PH_3, phosphorus is less electronegative than hydrogen, so phosphorus will be the central atom.

Connect each hydrogen atom to the central phosphorus atom with a single bond. Each P-H bond will use 2 valence electrons, so 3 bonds will use 6 electrons.

Distribute the remaining valence electrons to satisfy the octet rule for the central atom. After forming the bonds, 2 electrons remain, which will be placed as a lone pair on the phosphorus atom.

Verify that all atoms have a complete valence shell. Hydrogen atoms are satisfied with 2 electrons each, and phosphorus has 8 electrons around it (6 from bonds and 2 from the lone pair).

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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.

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 molecule's reactivity and stability. For example, phosphorus (P) has five valence electrons, which play a key role in forming bonds in molecules like PH3.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is influenced by the number of bonding pairs and lone pairs of electrons around the central atom. In the case of PH3, the geometry is trigonal pyramidal due to the presence of one lone pair on phosphorus, affecting the molecule's shape and properties.