GChemPaint/C3/Resonance-Structures/English-timed
From Script | Spoken-Tutorial
Title of the tutorial: Resonance Structures
Author: Madhuri Ganapathi
Key words: Show Electron shift and Resonance Structures, Create a reaction pathway, Create a mesomeric pathway, Build Retrosynthetic Pathway, Video tutorial.
| Time | Narration |
| 00:01 | Hello everyone. |
| 00:02 | Welcome to this tutorial on Resonance Structures in GChemPaint. |
| 00:06 | In this tutorial, we will learn to, |
| 00:09 | * Use different types of arrows to represent chemical reactions and |
| 00:14 | * Add charge and electron pairs on an atom |
| 00:18 | For this tutorial I am using |
| 00:20 | Ubuntu Linux OS version 12.04. |
| 00:24 | GChemPaint version 0.12.10. |
| 00:29 | To follow this tutorial you should be familiar with GChemPaint. |
| 00:34 | If not, for relevant tutorials, please visit our website. |
| 00:39 | I will switch to GChemPaint window. |
| 00:42 | I have opened a new GChemPaint window.
|
| 00:45 | Here you can see EthylChloride and Methylbromide structures. |
| 00:50 | I will show how to obtain a Carbo-cation. |
| 00:55 | Let's add a pair of electrons on the Chlorine atom of EthylChloride. |
| 01:01 | Click on Add an electron pair tool. |
| 01:04 | Click on Chlorine atom and observe what happens. |
| 01:09 | Next, I will show an electron pair shift in the Carbon-Chlorine bond. |
| 01:14 | Click on Add a curved arrow to represent an electron pair move tool. |
| 01:18 | Property window opens. |
| 01:21 | Click on End arrow at center of new bond check box. |
| 01:26 | It moves the electron pair to the correct position. |
| 01:30 | Click on Carbon-Chlorine bond. |
| 01:33 | Place the cursor on the curved arrow and observe the electron shift. |
| 01:39 | I will make the copy of this structure. |
| 01:42 | Now, click on Add an arrow and click between the structures. |
| 01:48 | Formation of a Carbo-cation is initialized by a base like Sodium Hydroxide(NaOH). |
| 01:54 | Click on Add or modify a group of atoms tool, click above the arrow. |
| 02:00 | Type NaOH. |
| 02:04 | Click on Selection tool and select NaOH. |
| 02:09 | Right-click on the arrow. |
| 02:12 | In the submenu, select Arrow. |
| 02:13 | Click on Attach selection to arrow. |
| 02:18 | A dialogue box with heading Arrow associated appears. |
| 02:23 | In the Role drop-down, select “Reactant” and click on Close. |
| 02:29 | Now, let's convert second EthylChloride to Ethyl Carbo-cation and Chloride ions. |
| 02:36 | Click on Eraser tool and click on Carbon-chlorine bond.
|
| 02:42 | Ethane(CH3-CH3) and HCl are formed. |
| 02:45 | When electrons shift from Carbon to Chlorine, Carbon gains a positive charge. |
| 02:51 | Click on Increment the charge tool. |
| 02:54 | Click at the position from where Carbon-chlorine bond was deleted. |
| 02:59 | Ethyl Carbo-cation(CH3-CH2^+) is formed. |
| 03:02 | To form Chloride ion, click on Decrement the charge tool. |
| 03:07 | Click on HCl. Chloride(Cl^-) ion is formed.
|
| 03:12 | Now let's move to single electron shift. |
| 03:15 | Let's use the Methylbromide structure to obtain free radicals. |
| 03:20 | Click on Add a curved arrow to represent a single electron move tool. |
| 03:26 | Click on Methylbromide bond to obtain a curved arrow. |
| 03:30 | Shift the Pencil tool a little on the bond, click again to get second curved arrow. |
| 03:38 | One arrow moves to bromo(Br) and other arrow moves towards methyl(CH3). |
| 03:44 | Both Bromo(Br) and methyl(CH3) will get one electron each from the bonded pair of electrons. |
| 03:51 | To show the products, let us add an arrow. |
| 03:54 | Click on Add an arrow, click on Display area beside Methylbromide. |
| 04:00 | Formation of free radicals involves heat in the reaction. |
| 04:04 | Click on Add or modify a text tool. |
| 04:08 | Click on the Display area above the arrow. |
| 04:11 | Type “Heat” in the green box. |
| 04:14 | Click on Selection tool and select “Heat” |
| 04:19 | Right-click on the arrow. |
| 04:21 | In the Submenu select Arrow and Click on Attach selection to arrow. |
| 04:27 | A dialogue box with heading Arrow associated appears. |
| 04:32 | Notice that Role drop down list has more options. |
| 04:37 | In the Role drop-down, select “Temperature” and |
| 04:40 | click on Close. |
| 04:43 | Now let's create the free radicals. |
| 04:46 | I will make a copy of this structure. |
| 04:50 | Click on Eraser tool and click on Carbon-bromine bond. |
| 04:55 | Methane(CH4) and Hydrogen-bromide(HBr) are formed. |
| 04:59 | Click on Add an unpaired electron tool. |
| 05:02 | Click on Methane(CH4) and Hydrogen-bromide(HBr) |
| 05:06 | Methyl(CH3) and Bromium(Br) free radicals are formed. |
| 05:10 | Click on Selection tool. |
| 05:12 | To create a reaction pathway, first select the complete reaction. |
| 05:17 | Now, right-click on the selection. |
| 05:20 | A submenu opens. |
| 05:22 | Click on Create a new reaction. |
| 05:25 | Reaction path is created. |
| 05:28 | Drag to see the reaction pathway. |
| 05:30 | Likewise, I will create the reaction pathway for the previous reaction. |
| 05:37 | We can also remove the reaction pathway, if we want to. |
| 05:41 | To do so, right-click on the reaction again |
| 05:45 | Click on Destroy the reaction. |
| 05:48 | This action will remove the reaction pathway. |
| 05:51 | Drag any of the objects, and you will see that they can be moved individually. |
| 05:57 | Now we move on to Resonance or Mesomery using double headed arrow. |
| 06:02 | I have opened a new GChemPaint window with structures of Nitromethane. |
| 06:08 | I had added curved arrows and charges to show electron shifts within the structures. |
| 06:14 | Now let's add a double headed arrow. |
| 06:16 | Click on Add a double headed arrow. |
| 06:20 | Click on the Display area in between Nitromethanes. |
| 06:25 | The two structures are "Resonance structures" of Nitromethane.. |
| 06:30 | Press CTRL+A to select the structures. |
| 06:33 | Right-click on the selection. |
| 06:35 | A submenu opens. |
| 06:37 | Click on Create a new mesomery relationship. |
| 06:41 | Drag to see the relationship. |
| 06:44 | Here is slide for the Resonance Structures of Benzene. |
| 06:48 | Now, let's learn to create a retro-synthetic pathway. |
| 06:52 | I have opened a new GChemPaint window with the required structures. |
| 06:57 | Retrosynthetic pathway starts with the product and goes to the reactant
along with all the intermediates. |
| 07:04 | In this pathway, the final product is Ortho-nitrophenol and the starting material is Benzene. |
| 07:10 | Let us add a retro-synthetic arrow, to show the retro-synthetic pathway. |
| 07:15 | Click on Add an arrow for a retrosynthetic step. |
| 07:20 | Click between all the compounds. |
| 07:25 | Press CTRL+A to select the structures. |
| 07:28 | Right click on the selection. |
| 07:30 | A sub-menu opens. |
| 07:32 | Click on Create a new retrosynthesis pathway. |
| 07:36 | Drag to see the created pathway. |
| 07:39 | Let's summarize what we have learnt. |
| 07:41 | In this tutorial we have learnt to |
| 07:44 | * Show electron shifts using curved arrows |
| 07:48 | * Attach reaction conditions to reaction arrows. |
| 07:52 | * Create and destroy reaction pathway using a reaction arrow |
| 07:57 | * Create a new mesomery relationship using double headed arrow |
| 08:01 | * Create a retro-synthetic pathway using retro-synthetic arrow. |
| 08:06 | As an assignment |
| 08:07 | Using arrow properties |
| 08:10 | 1. Create a reaction pathway for the reaction of Bromo-Ethane (C2H5Br) and Sodium(Na) with solvent Dryether to get Butane & Sodiumbromide. |
| 08:20 | 2. Add stoichiometric coefficients to reaction molecules. |
| 08:24 | 3. Draw resonance structures of Naphthalene, Anthracene and Carbon-dioxide |
| 08:30 | This is the required reaction pathway. |
| 08:33 | These are the resonance structures of Naphthalene, Anthracene and Carbon-dioxide. |
| 08:39 | Watch the video available at this URL. |
| 08:43 | It summarizes the Spoken Tutorial project |
| 08:45 | If you do not have good bandwidth, you can download and watch it |
| 08:50 | The Spoken Tutorial Project Team Conducts workshops using spoken tutorials |
| 08:54 | Gives certificates to those who pass an on-line test |
| 08:57 | For more details, please write to contact@spoken-tutorial.org |
| 09:03 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 09:08 | It is supported by the National Mission on Education through ICT, MHRD, Government of India
|
| 09:16 | More information on this Mission is available at this link |
| 09:21 | This is Madhuri Ganapathi from IIT Bombay signing off. Thank you for joining.
|
