Editing molecules – Nepali

Editing molecules – Nepali


Hello everyone. Welcome the tutorial on Editing Molecules in GChemPaint. In this tutorial, we will learn to * Add unbound electrons on an atom * Draw Carbonic acid and Sulphuric acid structures. * Add and modify a local charge on a group of atoms We will also learn to, * Add and modify a local charge on an atom * Add cyclic molecules * Convert mono-cyclic molecules to bi-cyclic molecules. Here I am using Ubuntu Linux OS version. 12.04 GChemPaint version 0.12.10 To follow this tutorial you should be familiar with, GChemPaint chemical structure editor. If not, for relevant tutorials, please visit our website. I have opened a new GChemPaint application. Let’s first draw Ammonia structure. Click on Current element drop down arrow button. Select N from the table. Observe N in the tool box. Click on Add or modify an atom tool. Then click on Display area. NH3 is seen on the Display area. Press capital H. A Submenu with a list of elements starting with H appears. Select H from the list. Click on Add a bond or change the multiplicity of the existing one tool. To draw three bonds to Nitrogen atom Click and drag the bonds thrice on Nitrogen atom. Orient the bonds to form a Pyramid like structure. Let us add a pair of un-bound electrons on Nitrogen atom. Click on Add an electron pair to an atom tool. Then click on Nitrogen atom of Ammonia. Observe the changes. Note that Nitrogen of Ammonia now has a pair of electrons. This pair does not take part in bonding. This pair of electrons is lone pair. As an assignment, * Draw Phosphorus trichloride structure * Add a pair of un-bound electrons on the Phosphorus atom. Now let’s draw ‘Carbonic acid(H2CO3) and Sulphuric acid(H2SO4) structures. Here is a slide for, Carbonic acid and Sulphuric acid structures. First let us move Ammoniastructure aside. To do so, click on Select one or more objects tool. Then click on Ammonia structure and drag it to one side. Now let’s draw Carbonic acid structure. Click on the Current element drop-down arrow button. Select C from the table. Click on Add a bond or change the multiplicity of the existing one tool. Click on the Display area. Orient three bonds in such a way that they form an inverted Y. Draw the fourth bond as a double bond to any one of the bonds. Now click on Current element drop down arrow button. Select O. Click on Add or modify an atom tool Place the cursor near the bonds. Click on the three bond positions. Carbonic acid(H2CO3) structure is drawn. Now let’s draw Sulphuric acid structure. Click on Current element drop down arrow button. Select S Click on Add or modify an atom tool. Then click on Display area. Observe H2S. Now anywhere on the Display area press capital O A Submenu with 2 options O and Os opens. Select O. Click on Add or modify an atom tool. Then click on Add a bond or change the multiplicity of the existing one tool. In the Property menu, increase the Bond length value to 200 or above. Click on H2S to draw three bonds of OH to S. Observe a positive charge near S. This appears because Sulphur has to satisfy valency of 6. For the fourth bond, first click on S . Now drag the bond to one side without releasing the mouse. Now let us convert the opposite bonds into double bonds. Click on Add a bond or change the multiplicity of the existing one tool. Then click on the opposite existing bonds of the structure. Note that the positive charge is no longer visible. Sulphuric acid structure is complete. Next let us add a local charge on the Carbonic acid and Sulphuric acid structures. To show local charge, Click on Decrement the charge of an atom tool. Click on the two O-H groups of the Carbonic acid structure. Observe that Carbonate ion CO32- is formed. To show the local charge on Sulphuric acid structure. Click on Decrement the charge of an atom tool. Click on the two opposite O-H groups of Sulphuric acid. Observe that Sulphate ion SO42- is formed. As an assignment, * Draw Nitric acid (HNO3) structure * Show the local charge on the Nitrate ion(NO-3) Your completed assignment should look like this. Let me quickly demonstrate how to add a local charge on an atom. Anywhere on the Display area, press capital N. A Submenu opens in which we will select Na. Click on Add or modify an atom tool Then click on the Display area. Sodium atom appears on the Display area. Click on Increment the charge of an atom tool. Then Click on Na. Observe a positive charge on the Sodium atom. In a similar way, we can add a negative charge to an atom. This can be done by choosing Decrement the charge of an atom tool. Now let us learn to draw Cyclic molecules. For this, we will open a new GChemPaint window. Click on Create a new file icon on the toolbar. Ensure that C that is Carbon is selected as element. Also, ensure that Bond length is 200 or above. The Fourth toolbar in the tool box is the Cycle tool There are various tools here that we can use. For eg – * Add a three membered cycle * Add a four membered cycle * And some more cycle tools and then * Add a cycle tool. We will use Add a four membered cycle. So, click on it. Then click on the Display area. Let us add atoms to the cycle at the corners. Right click on any one of the corners. A Submenu opens. Select Atom and then click on Display symbol. Likewise let us add atoms on all the corners. Obtained structure is Cyclobutane. Now let us convert a mono-cyclic compound to bi-cyclic compound. Click on Add a six membered cycle tool. Then click on Display area. Place the cursor on the cycle’s bond and click again. Observe the Bi-cyclic compound. To save the file, Click on Save the current file icon on the toolbar. Save as dialogue box opens. Enter the file name as Editing Molecules Click on Save button. Let’s summarize. In this tutorial, we have learnt to, * Add unbound electrons on an atom * Draw Carbonic acid and Sulphuric acid structures. * Add and modify a local charge on a group of atoms We have also learnt to, * Add and modify a local charge on an atom * Add cyclic molecules * Convert mono-cyclic molecules to bi-cyclic molecules. As an assignment * Add a seven membered cycle to the Display area * Change it to a tricyclic compound. Watch the video available at this URL. http://spoken-tutorial.org/ What_is_a_Spoken_Tutorial It summarises the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it. The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to [email protected] Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at this link http://spoken-tutorial.org/NMEICT-Intro This is Madhuri Ganapathi from IIT Bombay signing off. Thank you for joining.

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