Difference between revisions of "PhET-Simulations-for-Chemistry/C2/Molecules-and-Geometry/English"

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Latest revision as of 13:47, 15 February 2023

Title of script: Molecules and Geometry

Author: Radhika Yadav

Keywords: PhET simulation, molecules, molecular geometry, electron geometry, molecular structure, bonds, bond angles, lone pairs, VSEPR theory, spoken tutorial, video tutorial.


Visual Cue Narration
Slide Number 1

Title Slide

Welcome to this Spoken Tutorial on Molecules and Geometry.
Slide Number 2

Learning Objectives

In this tutorial, we will learn how to:
  • Add and delete bonds and lone pairs
  • Identify different molecular geometries
  • Differentiate between electron and molecular geometries.
Slide Number 3

System Requirements

This tutorial is recorded using,

macOS Catalina version 10.15.7

Google Chrome version 101.0.49

Slide Number 4

Pre-requisites


https://spoken-tutorial.org


To follow this tutorial,

Learners should be familiar with topics in basic chemistry.


Please use the link below to access the tutorials on PhET simulations.

Slide Number 5

Link for PhET simulation


https://phet.colorado.edu/en/simulations/molecule-shapes


Please use the given link to download the PhET simulation.
Slide Number 6

PhET simulations

In this tutorial, we will use,


Molecule Shapes PhET simulation.

Point to the simulation in the Downloads folder


Molecule Shapes simulation.

I have already downloaded the simulation to my Downloads folder.
Double click on the molecule-shapes_en.html file To open the simulation, double click on the molecule-shapes_en.html file.


The file opens in your default browser.

Point to the simulation interface This is the interface of the Molecule Shapes simulation.
Open Settings menu at the bottom right.

Choose Options >> select Projector Mode.

Click on X button.

Click on the Settings menu list next to the PhET logo at the bottom right.


Choose Options and then check on Projector Mode.


This will display the simulation in a light background.

Close the menu.

Point to each screen The interface has two screens,


Model and Real Molecules

Click on the Model screen Click on the Model screen.
Point to the molecule in the centre of the screen In the centre, we have a model molecule.


We can add and delete bonds and lone pairs to this molecule.

Point to the Bonding box at the top right.

Click on the bond type to add to the molecule.


Click the red cross button to remove the bond.

At the top right, we have Bonding box with single, double and triple bonds.


Click on the bond type to add to the molecule.


We can remove the bonds using the red cross button next to the bond type.

Point to the Lone Pair box


Click on the icon to add a lone pair.


Click on the red cross button to remove it.

Show arrow annotation to the violet ball in the model(3.01 to 3.12 min)

Below the Bonding box, we have the Lone Pair box.


We can add a lone pair to the molecule by clicking on the icon.

We can remove it by clicking on the red cross next to it.


A lone pair is an electron pair in the outermost shell of an atom.

It is bonded to the central atom in a molecule.

Point to the Remove All option The Remove All button removes all atoms and their bonds in the molecule.
Point to the Options box Options box at the bottom, has Show Lone Pairs, and Show Bond Angles checkboxes.


We can use these check boxes to show and hide the details.


Bond angle is the angle between two bonds that share a common atom.

Point to the Name box at the bottom right The Name box at the bottom left has

Molecule Geometry and Electron Geometry checkboxes.


Here, geometry means the three-dimensional arrangement of atoms in a molecule.


Molecule geometry is found using only the bonds in a molecule.


Electron geometry is found using the bonds and electron pairs in a molecule.

Click the reset button. The reset button will take us back to the start of the simulation.
Check the Molecule Geometry and Electron Geometry checkboxes Check the Molecule Geometry and Electron Geometry checkboxes.


Both are Linear for this molecule.

Check the Show Bond Angles checkbox.


Point to the bond angle of the bond.

Check the Show Bond Angles checkbox.


The bond angle is shown as 180 degrees.

Click on the double bonded atom in the Bonding box Let us add a double bonded atom to the molecule.
Point to the Name box The Molecule and Electron geometries are Trigonal Planar.
Point to the molecule The bond angle between each bond is 120 degrees.
Click on the lone pair atom in the Lone Pair box Let us add a lone pair of electrons to the molecule.
Point to the Name box The molecule geometry is Trigonal Pyramidal.


However, the Electron geometry is now Tetrahedral.

Point to the molecule The bond angle between each bond is 109.5 degrees.
Click on the triple bonded atom in the Bonding box Let us now add a triple bonded atom to the molecule.
Point to the Name box The Molecule geometry is Seesaw.


The Electron geometry is Trigonal Bipyramidal.

Point to the molecule The bond angle between a single bond and the double bond is 120 degrees.


All other bond angles are 90 degrees.

Slide Number 7

Assignment


  • Molecule- Bent, Electron- Tetrahedral
  • Molecule- Linear, Electron- Trigonal Bipyramidal
  • Molecule- T-Shaped, Electron- Octahedral
As an assignment, build molecules that have the following geometries.


Click on the Real Molecules screen Click on the Real Molecules screen.


The screen has some new tools.

Point to the Real and Model options at the top There are two options to view the molecule at the top.


The first is the Real option to show the actual shape of the molecule.


Select the Model option

Select the Real option

The second is the Model option to show the shape predicted by the VSEPR model.


It stands for Valence Shell Electron Pair Repulsion model.


There are repulsions between bond pairs and lone pairs.


VSEPR assumes that these pairs will arrange themselves to minimize the repulsion effects.

Point to the Molecule box At the top right, we have a Molecule dropdown.


We can select a real molecule from the given drop down list.

Water molecule (H2O) is selected by default.

Point to the molecule This is the water molecule.


It has 2 single bonded atoms and 2 lone pairs.

Open settings menu and select Show Outer Lone Pairs

Click on X button.

Click on the Settings menu list next to the PhET logo at the bottom right.


Choose Options and then check on Show Outer Lone Pairs.


This will display lone pairs of all the atoms in the molecule.


Close the menu.

Point to the molecule In the water molecule, only oxygen atom has 2 lone pairs.
Check the Molecule Geometry and Electron Geometry checkboxes Check the Molecule Geometry and Electron Geometry checkboxes.


The Molecule Geometry is Bent.

The Electron Geometry is Tetrahedral.

Check the Show Bond Angles checkbox Check the Show Bond Angles checkbox.
Point to the molecule The bond angle between the two single bonds is 104.5 degrees.
Click on the Model option Click on the Model option.
Point to the molecule The VSEPR model predicts the bond angle to be 109.5 degrees.


We have seen the actual angle is 104.5 degrees.


This is because a water molecule has 2 lone pairs.


The repulsion between the lone pairs causes distortion in the actual bond angle.

Click on the Real option Click on the Real option again.
Select XeF4 molecule from the drop down list Let us select another molecule from the drop down list.
Point to the molecule This is Xenon tetrafluoride (XeF4) molecule.
Open Settings menu and unselect Show Outer Lone Pairs check box. We can hide the outer lone pairs of the molecule.
Point to the molecule The molecule has 4 single bonds and 2 lone pairs on the central atom.
Point to the Name box The Molecule Geometry is Square Planar.

The Electron Geometry is Octahedral.

Point to the molecule Click on the screen near the molecule to move the molecule around.

Change its perspective such that all bond angles are visible.


The bond angle between each of the four single bonds is 90 degrees.

Click on the Model option Click on the Model option.
Point to the molecule In this case, the bond angle remains the same.


There is no lone pair-lone pair or single bond-lone pair repulsion.

Slide Number 8

Assignment

As an assignment,

Check the geometries of all remaining molecules in the list.


Compare their real and model-predicted bond angles.


Explain the reasons for the differences.

Only Narration. With this, we have come to the end of this tutorial.

Let us summarise.

Slide number 9

Summary

In this tutorial, we have learnt how to:


  • Add and delete bonds and lone pairs
  • Identify different molecular geometries
  • Differentiate between electron and molecular geometries.
Slide number 10

About the Spoken Tutorial project

The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

Slide number 11

Spoken Tutorial workshops

The Spoken Tutorial Project team:

conducts workshops using spoken tutorials and

gives certificates on passing online tests.

For more details, please write to us.

Slide number 12

Forum for specific questions


Do you have questions in THIS Spoken Tutorial?

Please visit this site.

Choose the minute and second where you have the question.

Explain your question briefly.

The Spoken tutorial project will ensure an answer.

You will have to register to ask questions.


Please post your timed queries in this forum.
Slide number 13

Acknowledgement

The Spoken Tutorial project is funded by the Ministry of Education, Government of India.
Slide number 14

Thank you

This is Radhika Yadav, a FOSSEE summer fellow 2022, IIT Bombay signing off.


Thanks for joining.

Contributors and Content Editors

Madhurig, Snehalathak

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