Electronegativity and Polarity Electronegativity: A measure of an atom’s ability to attract electrons in a bond. Polarity Rules: Non-Polar Bonds: Identical atoms (e.g., H₂) have no difference in electronegativity. Polar Covalent Bonds: Differences in electronegativity between 0.5 and 1.7. Ionic Bonds: Differences in electronegativity greater than 1.7. Key Bonds and Their Polarities Carbon-Hydrogen Bond: Non-polar (difference in electronegativity = 0.4). Carbon-Nitrogen Bond: Polar covalent (difference = 0.5). Carbon-Oxygen Bond: Polar covalent (difference = 1.0). Carbon-Fluorine Bond: Polar covalent (difference = 1.5, approaching ionic character). Sodium-Chloride Bond: Ionic (difference = 2.1). Exceptions Carbon-Magnesium Bond: Despite being a metal and a non-metal, this bond is polar covalent (difference = 1.3), not ionic. Identifying Polar Molecules Step 1: Look for polar bonds within the molecule. Step 2: Check the orientation of these polar bonds: If the vector sum of bond dipoles cancels out, the molecule is non-polar. If the vector sum does not cancel out, the molecule is polar. Examples of Molecular Polarity Carbon Dioxide (CO₂): Non-polar because the bond dipoles cancel out (linear shape, bond angles of 180°). Carbonyl Sulfide (COS): Polar because the bond dipoles do not cancel out (due to different electronegativities of oxygen and sulfur). Methane (CH₄): Non-polar with no polar bonds. Chloromethane (CH₃Cl): Polar with a dipole moment of 1.87 D. Dichloromethane (CH₂Cl₂): Less polar than CH₃Cl (dipole moment of 1.6 D) due to the bond angles causing partial cancellation. Trichloromethane (CHCl₃): Even less polar (dipole moment of 1.01 D). Tetrachloromethane (CCl₄): Non-polar as the four polar bonds cancel out. Dipole Moments Definition: A measure of the polarity of a molecule, represented by the symbol μ. Calculation: Depends on the difference in partial charges and the distance of separation.
O my teacher ,a great teacher,a healthy teacher,a man with a full of kindness,a man with a lot of comments along with his videos.I want to become a teacher like you and also want to become a doctor 😊
Are you still giving out your free one month code for the new test prep study courses. I was going to sign up today but the code disappeared. I am studying for the DAT! :D
Sorry, this playlist is my latest for Ochem. Working through a Physics playlist this school year and planning on a new Biochemistry playlist next school year. Trying to keep pace with one new playlist per year.😊
might be to late but I watched a video from the organic chemistry tutor. The higher EN number an atom has means it will be partially negative aka arrow facing that way. idk what he means by "adding them up" but from my understanding if the arrows are facing opposite ways or towards each other they will cancel out and dipole will be exactly 0 meaning it is non polar.
Sir the time in the video is 5:40 ok. Sir as you said that the 90 angle is the threshold if the angle becomes greater than 90 then the dipole moments would cancel each other more than they add up e.g at 109.5 angle Even though at this angle the dipoles are not exactly opposite in direction so how they do cancel??
Sir if 3 out of 4 atoms around the carbon are exactly same then you said that molecule has a dipole moment but sir if we look at the compound having carbon as centre and surrounding 4 chlorines then these exactly cancel their dipole moments making a non polar molecule .The question is that why those 3 chlorines in the previous example don't cancel out their dipole moments as they exactly cancel in the second example???
@@ChadsPrep e.g central carbon attached with 3 flourines and 1 hydrogen in a tetrahedral shape having bond angle 109.5 degrees so sir in this case the bond angle is not exactly opposite between individual dipole moments so you are saying that they will cancel more than they add up . How is that??
@@ChadsPrep ok sir when 90 degree is the threshold for the direction of bond dipoles and if the direction of bond dipoles is less than 90 degree they will simply add up and when the direction of bond dipoles is greater than 90 degree they will cancel more than they add up. Well sir what does the last statement means?
Would you classify a ketone as more stable than a secondary alcohol? Does the bond strength in ketone increase the stability? Also, say we had a C=O attached to EWGs, and C=O attached to EDGs, which would be more stable? Some speak of the stability of the carbonyl carbon, and that EWGs would make it less stable, but wouldn't the one with EWGs be pulling in the opposite direction to C=O and therefore stabilize it, like in CO2 where one C=O is pulling one side and another C=O is pulling another?
Hey Youssef - typically we refer to a molecule as being more stable when it is less reactive, but it really depends whether we are talking about thermodynamic or chemical stability. The O-H bond is weaker than the C=O bond and so is thermodynamically less stable, but C=O groups are much more reactive to nucleophillic attack which gives them more chemical instability. Likewise if we are talking about C=O as an electrophile and looking at its chemical stability then for nucleophilic attack we want the C to be as positive as possible (it carries a partial positive charge when bonded with oxygen) if there is a donating group next to the carbonyl it would reduce the positive charge and this makes the molecule more chemically stable as it is less vulnerable to nucleophilic attack. In terms of thermodynamic stability we can look at the effect of a donating group on the C=O bond. The C=O bond is particularly stable because the charge is distributed by resonance (which stabilizes molecules). Donating groups push more electrons onto the carbon which disrupts the resonance structure whereas withdrawing groups help the resonance structure. So we can look at it in multiple ways but I hope that helps your reasoning!
Sir if 3 out of 4 atoms surrounding a carbon are same and the fourth atom is let's say hydrogen ok then these 3 similar atoms having same dipole moments don't cancel their dipole moments exactly to form a non polar molecule . But if we have a compound having carbon as center and surrounding with4 similar atoms then they exactly cancel out their dipole moments making a molecule completely non polar . The question is that why the similar atoms around central atom Don't exactly cancel their dipole moments as those similar atoms in the second example completely cancel their dipole moments making a molecule non polar??
Are you asking why carbon with 3 bonds to the same atom and one bond to a different atom is polar? The structure is tetrahedral, so cross-shaped. The two same atoms opposite eachother will cancel out but the two different atoms opposite each other will not cancel leaving a resultant dipole. It is that extra, non-equivalent atom that throws everything off and leads to the dipole because it will have a different negativity than the others.
@@ChadsPrep sir I just understand it because I took the vector sum of individual bond dipoles . Sir in CHF3 it seems like a nonpolar molecule because the three florines cancel the effect of their individual bond dipoles and remaining C_H bond is also nonpolar so the overall molecule seems nonpolar but the truth is that if we take the vector sum of individual bond dipoles then it shows a resultant molecular dipole which make it a polar molecule. Am l right sir.
What is the real truth for knowing that whether a molecule is polar or not? Because in CHF3 it's molecular geometry and also c_H bond gives the idea that the overall molecule is nonpolar .But by vector addition anyone could be able to prove that it is a polar .sir in which thing : molecular geometry,bond polarities in molecules, vector addition we should believe during the selection of molecular polarity?
Electronegativity and Polarity
Electronegativity: A measure of an atom’s ability to attract electrons in a bond.
Polarity Rules:
Non-Polar Bonds: Identical atoms (e.g., H₂) have no difference in electronegativity.
Polar Covalent Bonds: Differences in electronegativity between 0.5 and 1.7.
Ionic Bonds: Differences in electronegativity greater than 1.7.
Key Bonds and Their Polarities
Carbon-Hydrogen Bond: Non-polar (difference in electronegativity = 0.4).
Carbon-Nitrogen Bond: Polar covalent (difference = 0.5).
Carbon-Oxygen Bond: Polar covalent (difference = 1.0).
Carbon-Fluorine Bond: Polar covalent (difference = 1.5, approaching ionic character).
Sodium-Chloride Bond: Ionic (difference = 2.1).
Exceptions
Carbon-Magnesium Bond: Despite being a metal and a non-metal, this bond is polar covalent (difference = 1.3), not ionic.
Identifying Polar Molecules
Step 1: Look for polar bonds within the molecule.
Step 2: Check the orientation of these polar bonds:
If the vector sum of bond dipoles cancels out, the molecule is non-polar.
If the vector sum does not cancel out, the molecule is polar.
Examples of Molecular Polarity
Carbon Dioxide (CO₂): Non-polar because the bond dipoles cancel out (linear shape, bond angles of 180°).
Carbonyl Sulfide (COS): Polar because the bond dipoles do not cancel out (due to different electronegativities of oxygen and sulfur).
Methane (CH₄): Non-polar with no polar bonds.
Chloromethane (CH₃Cl): Polar with a dipole moment of 1.87 D.
Dichloromethane (CH₂Cl₂): Less polar than CH₃Cl (dipole moment of 1.6 D) due to the bond angles causing partial cancellation.
Trichloromethane (CHCl₃): Even less polar (dipole moment of 1.01 D).
Tetrachloromethane (CCl₄): Non-polar as the four polar bonds cancel out.
Dipole Moments
Definition: A measure of the polarity of a molecule, represented by the symbol μ.
Calculation: Depends on the difference in partial charges and the distance of separation.
O my teacher ,a great teacher,a healthy teacher,a man with a full of kindness,a man with a lot of comments along with his videos.I want to become a teacher like you and also want to become a doctor 😊
Very kind words, thank you and I hope your plans become a reality!
@@ChadsPrep thank u sir
Thanks chad!
Your'e welcome!
Are you still giving out your free one month code for the new test prep study courses. I was going to sign up today but the code disappeared. I am studying for the DAT! :D
Do you have '23-'24 year curriculum for OChem? Your previous one was outstanding!!!!🙂
Sorry, this playlist is my latest for Ochem. Working through a Physics playlist this school year and planning on a new Biochemistry playlist next school year. Trying to keep pace with one new playlist per year.😊
What are you calculating to get the dipole moment?
might be to late but I watched a video from the organic chemistry tutor. The higher EN number an atom has means it will be partially negative aka arrow facing that way. idk what he means by "adding them up" but from my understanding if the arrows are facing opposite ways or towards each other they will cancel out and dipole will be exactly 0 meaning it is non polar.
He's calculating the differential in electronegativity of the two bonding atoms
Sir the time in the video is 5:40 ok. Sir as you said that the 90 angle is the threshold if the angle becomes greater than 90 then the dipole moments would cancel each other more than they add up e.g at 109.5 angle Even though at this angle the dipoles are not exactly opposite in direction so how they do cancel??
Sir if 3 out of 4 atoms around the carbon are exactly same then you said that molecule has a dipole moment but sir if we look at the compound having carbon as centre and surrounding 4 chlorines then these exactly cancel their dipole moments making a non polar molecule .The question is that why those 3 chlorines in the previous example don't cancel out their dipole moments as they exactly cancel in the second example???
Can you give me the formula of the molecule you are looking at?
@@ChadsPrep e.g central carbon attached with 3 flourines and 1 hydrogen in a tetrahedral shape having bond angle 109.5 degrees so sir in this case the bond angle is not exactly opposite between individual dipole moments so you are saying that they will cancel more than they add up . How is that??
If it is tetrahedral then the opposite bonds do cancel if the atoms are all the same, but the F and H do not cancel since they are not the same
@@ChadsPrep ok sir when 90 degree is the threshold for the direction of bond dipoles and if the direction of bond dipoles is less than 90 degree they will simply add up and when the direction of bond dipoles is greater than 90 degree they will cancel more than they add up. Well sir what does the last statement means?
Would you classify a ketone as more stable than a secondary alcohol? Does the bond strength in ketone increase the stability?
Also, say we had a C=O attached to EWGs, and C=O attached to EDGs, which would be more stable? Some speak of the stability of the carbonyl carbon, and that EWGs would make it less stable, but wouldn't the one with EWGs be pulling in the opposite direction to C=O and therefore stabilize it, like in CO2 where one C=O is pulling one side and another C=O is pulling another?
Hey Youssef - typically we refer to a molecule as being more stable when it is less reactive, but it really depends whether we are talking about thermodynamic or chemical stability. The O-H bond is weaker than the C=O bond and so is thermodynamically less stable, but C=O groups are much more reactive to nucleophillic attack which gives them more chemical instability. Likewise if we are talking about C=O as an electrophile and looking at its chemical stability then for nucleophilic attack we want the C to be as positive as possible (it carries a partial positive charge when bonded with oxygen) if there is a donating group next to the carbonyl it would reduce the positive charge and this makes the molecule more chemically stable as it is less vulnerable to nucleophilic attack. In terms of thermodynamic stability we can look at the effect of a donating group on the C=O bond. The C=O bond is particularly stable because the charge is distributed by resonance (which stabilizes molecules). Donating groups push more electrons onto the carbon which disrupts the resonance structure whereas withdrawing groups help the resonance structure. So we can look at it in multiple ways but I hope that helps your reasoning!
Sir if 3 out of 4 atoms surrounding a carbon are same and the fourth atom is let's say hydrogen ok then these 3 similar atoms having same dipole moments don't cancel their dipole moments exactly to form a non polar molecule . But if we have a compound having carbon as center and surrounding with4 similar atoms then they exactly cancel out their dipole moments making a molecule completely non polar . The question is that why the similar atoms around central atom Don't exactly cancel their dipole moments as those similar atoms in the second example completely cancel their dipole moments making a molecule non polar??
Are you asking why carbon with 3 bonds to the same atom and one bond to a different atom is polar? The structure is tetrahedral, so cross-shaped. The two same atoms opposite eachother will cancel out but the two different atoms opposite each other will not cancel leaving a resultant dipole. It is that extra, non-equivalent atom that throws everything off and leads to the dipole because it will have a different negativity than the others.
@@ChadsPrep sir I just understand it because I took the vector sum of individual bond dipoles . Sir in CHF3 it seems like a nonpolar molecule because the three florines cancel the effect of their individual bond dipoles and remaining C_H bond is also nonpolar so the overall molecule seems nonpolar but the truth is that if we take the vector sum of individual bond dipoles then it shows a resultant molecular dipole which make it a polar molecule. Am l right sir.
What is the real truth for knowing that whether a molecule is polar or not? Because in CHF3 it's molecular geometry and also c_H bond gives the idea that the overall molecule is nonpolar .But by vector addition anyone could be able to prove that it is a polar .sir in which thing : molecular geometry,bond polarities in molecules, vector addition we should believe during the selection of molecular polarity?
I can't really explain it better in the comments than I do in the videos I'm afraid! Try watching the video again :)