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Hello everyone.

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Welcome the tutorial on Formation of bonds in GChemPaint.

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In this tutorial, we will learn to-

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* Add bonds to the existing bond

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* Orient the bonds

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* Add Stereochemical bonds and

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* Inverse wedge hashes.

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Here I am using Ubuntu Linux OS version. 12.04,

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GChemPaint version 0.12.10

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To follow this tutorial you should be familiar with,

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GChemPaint chemical structure editor.

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If not, for relevant tutorials,  please visit our website.

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I have opened a new GChemPaint application with Ethane structure.

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Let us learn to convert Saturated Hydrocarbons to Unsaturated Hydrocarbons.

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Let us copy the Ethane structure and paste it twice on the Display area.

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Click on  Select one or more objects tool.

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Click on Ethane structure to select it.

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Press Ctrl +C to copy  the structure

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and Press Ctrl + V to paste the structures.

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Observe that two structures overlap each other.

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Let's move the second overlapping structure aside.

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Place the cursor on  the structure and drag it with the mouse.

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Observe the single bond between the carbon atoms in the structures.

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Let's first convert single bond to a double bond.

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Click on Add a bond or change the multiplicity of an existing one tool.

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Click on the existing bond of the second  Ethane structure.

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Observe that single bond is converted to a double bond.

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Number of Hydrogen atoms reduced from 6 to 4.

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The new structure is Ethene.

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Next let's convert the single bond to a triple bond.

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Click on the existing bond of the third Ethane structure twice.

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Observe that Single bond is converted to a triple bond.

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Number of hydrogen atoms reduced from 6 to 2.

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The new structure is Ethyne.

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Let us write the names of the structures.

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Click on Add or modify a text tool.

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Click below the structures.

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Enter the names of the structures as  Ethane, Ethene and Ethyne.

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Next, let us learn about Tetrahedral geometry.

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Let's move the structures to a side.

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Press Ctrl+A to select all objects.

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Click on Select one or more objects tool and drag the structures.

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Here is a slide for the Tetrahedral Methane structure.

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All the bond lengths are equal to 1.09 angstrom.

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In  Tetrahedral methane structure, all the bond angles are equal to 109.5 degree.

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Now, let's draw Tetrahedral  Ethane structure.

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Click on Add a bond or change the multiplicity of existing one tool.

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Click on the Display area.

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Orient the bond in horizontal direction.

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On  each edge of the bond let us draw three bonds.

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Orient the bonds to form a Tetrahedral geometry.

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Click on each edge. Then orient the three bonds in different directions.

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Likewise let us draw on the other edge.

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Let us attach hydrogen atoms at the ends.

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To attach Hydrogen atoms to the ends, press capital H.

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A sub-menu opens in which we will select H.

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Observe that Hydrogen atom appears in the tool box.

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Click on Add or modify an atom tool.

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Click on all the positions to add hydrogen atoms.

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Now let us  add Stereochemical bonds to Ethane structure.

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Stereochemical bonds available in the tool box are,

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* Add a wedge bond

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* Add a hash bond

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* Add a squiggle bond

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* and Add a fore bond.

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Let us  use Add a wedge bond to convert Ethane to a  "Stereochemical" structure.

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Click on  Add a wedge bond.

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Then click on all the bonds.

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Observe the changes.

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Click on Add a hash bond

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and then click on the Display area.

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Now I will explain about Invert wedge hashes.

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Go to Edit menu, navigate to Preferences and click on it.

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GChemPaint Preferences window opens.

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Click on Invert wedge hashes check box.

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If set, the wedge hashes bonds will follow the usual convention.

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Narrow end is at the start of the bond and broad end is at the other end.

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This helps to visualize the bond correctly.

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Default convention in GChemPaint is inverse, because it is more consistent with the perspective rules.

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Observe the changes in the Hash bond.

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Let us click on Close button to close the window.

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Let us change the bonds to  Add a hash bond  in the Ethane structure.

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Click on  Add a hash bond.

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Click on all the bonds.

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Let us now save the file.

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Click on Save the current file icon on the toolbar.

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Save as dialog box opens.

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Enter the file name as Formation of  bond .

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Click on Save button.

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Let's summarise.

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In this tutorial we have learnt to,

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* Add bonds to the existing bond

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* Orient the bonds

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* Add Stereochemical bonds

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* and Inverse wedge hashes.

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As an assignment,

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* Convert Propane to Propyne

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* Draw Propane and butane structures

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* Show the stereochemical bonds.

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Your completed assignment should look like this.

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Watch the video available at this URL http://spoken-tutorial.org /What_a_Spoken_Tutorial.

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It summarizes the Spoken Tutorial project.

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If you do not have good bandwidth, you can download and watch it.

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The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials.

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Gives certificates to those who pass an online test.

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For more details, please write to contact@spoken-tutorial.org.

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Spoken Tutorial Project is a part of the Talk to a Teacher project.

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It is supported by the National Mission on Education through ICT, MHRD,Government of India.

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More information on this Mission is available at this link http://spoken-tutorial.org/NMEICT-Intro.

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Animation is done by Udhaya Chandrika.

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This is Madhuri Ganpathi from IIT Bombay signing off. Thank you for joining.