Describe the molecular geometry of: (a) H 2 Se

Hi everyone. So for this problem we need to find the molecular shapes for these molecules to do that. We're going to need to write out there lewis structures. So let's go ahead and do that. So for this first one we're going to have xenon in the middle and it's going to be surrounded by two florins. So florian gets seven valence electrons. So we can put 123456 around it and then it will get one from the bond and then we can go ahead and do that to the other one. And zenon because it's a noble gas gets eight valence electrons. So you'll have 12345678. This shape is going to be linear. So already we can kind of see that A is going to be our answer. But let's go through the rest anyway just to make sure. So next up we have H20. We're gonna have oh in the middle. And then to hydrogen is down here, The hydrogen czar happy, they just need one valence electron, but oxygen needs six. So it has one too. So we can add 3456 here. This is going to be bent. It kind of looks bent already but also because of the lone pairs surrounding oxygen. We have two lone pairs there. So that's going to be bent For BCL. three. We're going to have boron in the middle and we're going to have the chlorine surrounding it. Now chlorine needs seven valence electrons. So we're going to put 123456 And then it gets seven from the bond. And we can go ahead and do that to the other two. And boron is happy it has three electrons here. So we're all good to go there. This is going to be a Trigon aled planner and it kind of looks like a triangle. So if that helps you out, you can definitely use that to your advantage here. Finally, we have C. H four And we're going to have C in the middle and then four H is surrounding it. And the hse are all happy. They have one electron and carbon needs for which it gets from each of the bonds. So this is going to be a tetrahedron. And you can see from our order here, we're going to go linear bent Trigana planner and tetrahedron. And when you take a look at our choices, you're going to find that A is going to be our correct answer choice. I hope this video helped you out and I'll see you in the next one

Ch.22 - The Main Group Elements

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McMurry 8th Edition

Ch.22 - The Main Group Elements

Problem 62a

Chapter 22, Problem 62a

Describe the molecular geometry of:
(a) H₂Se

Verified step by step guidance

Identify the central atom in the molecule. For H2Se, selenium (Se) is the central atom because hydrogen (H) is typically a terminal atom.

Determine the number of valence electrons for the central atom. Selenium (Se) is in group 16 of the periodic table, so it has 6 valence electrons.

Count the total number of valence electrons in the molecule. Each hydrogen atom contributes 1 valence electron, so H2Se has a total of 6 (from Se) + 2 (from 2 H atoms) = 8 valence electrons.

Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the molecular geometry. Selenium will form two single bonds with hydrogen atoms, using 4 of its valence electrons, leaving 2 lone pairs on the selenium atom.

Based on the VSEPR theory, the presence of two bonding pairs and two lone pairs around the central atom (Se) results in a bent or angular molecular geometry, similar to that of water (H2O).

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Key Concepts

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

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) Theory is a model used to predict the geometry of individual molecules based on the repulsion between electron pairs in the valence shell of the central atom. According to this theory, electron pairs will arrange themselves as far apart as possible to minimize repulsion, leading to specific molecular shapes.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is determined by the number of bonding pairs and lone pairs of electrons around the central atom, which influences the overall shape, such as linear, bent, or tetrahedral. For H2Se, understanding its molecular geometry helps in predicting its physical and chemical properties.

Bond Angles

Bond angles are the angles formed between adjacent bonds in a molecule, which are influenced by the molecular geometry. In H2Se, the presence of lone pairs on the selenium atom affects the bond angles between the hydrogen atoms, leading to a bent shape. Understanding bond angles is crucial for predicting how molecules interact and behave in different chemical environments.