so what is the difference between a polar covalent bond and a non polar covalent bond well first need to know what is a covalent bond and how it differs from an ionic bond in a covalent bond electrons are shared so let's look at the example between two hydrogen atoms when two hydrogen atoms combine they get together and they form a covalent bond which looks like this so the covalent bond represents a sharing of electrons now when sodium metal reacts with chlorine gas or let's just say an atom of chlorine notice what happens chlorine has seven valence electrons sodium has one so sodium transfers one of its electrons to chlorine and so the sodium the sodium particle develops a positive charge so becomes an ion specifically a cation cations are positively charged and chlorine which now has eight electrons in its outermost energy level now has a negative charge and so these two ions are attracted to each other opposite charges attract each other so there is an electrostatic force that pulls them together and so that creates the ionic bond so ionic bonds are formed through the transfer of electrons and ionic bonds they're based on the electrostatic forces that pull positive and negative ions together whereas in a covalent bond the electrons are shared between two atoms so now that we know what a covalent bond is we could talk about what's a polar covalent bond and a nonpolar covalent bond so let's use H F and H H as an example hydrogen gas is a non-polar molecule so the bond is nonpolar HF has a polar bond now both of these bonds are covalent because electrons are being shared however in the nonpolar covalent bond you have equal sharing of electrons the reason why the sharin is equal because these two atoms are equivalent they're the same they have the same electronegativity value which is 2 point 1 in HF the electronegativity value is not the same fluorine is 4.0 and hydrogen's 2.1 so the difference is huge and so what we have is a polar covalent bond the reason why it's a polar covalent bond is because you have unequal sharing of electrons because fluorine is more electronegative than hydrogen fluorine is going to pull the electrons toward itself and so the electrons in HF they're going to spend more time closer to fluorine than to hydrogen and as a result fluorine is going to have a partial negative charge in hydrogen it's going to have a partial positive charge and whenever you have a molecule where one side is partially positive and the other side is partially negative what you have is a polar molecule this is a polarized object and so the HF bond is a polar covalent bond it causes the molecule to be polar when you have a non polar bond the electrons are distributed evenly in a polar bond once that has more electrons the other side has less so you have an unequal distribution of electrons now you can characterize bonds based on the electronegativity difference between the atoms so for example if you have a non-polar bond the electronegativity difference is typically between zero and point four now for polar covalent bond the electronegativity difference is about 0.5 to about 1.9 that Mo's and for an ionic bond it's usually 1.9 in more so let's just say greater than 1.9 just to keep it simple and if it's nonpolar you could say it's less than 0.5 now the best way to distinguish an ionic bond is to look for two things one is the composed of ions positive and negative charges two is a composed of a metal and a nonmetal that's the easiest way to distinguish an ionic bond and then to distinguish a polar covalent bond from a nonpolar covalent bond just look at the the electronegativity values if the difference is 0.5 or more then it's going to be a polar covalent bond in covalent bonds are typically composed of nonmetals so we see two nonmetals attached to each other it's usually a covalent bond if you have a metal and a nonmetal it's usually an ionic bond let's work on these problems identify the following bonds as ionic polar covalent or nonpolar covalent so feel free to work on this example so let's start with the chlorine molecule the bonding is molecule how would you describe it now if we have two nonmetals it's going to be a covalent bond chlorine is a nonmetal and if these nonmetals are the same automatically you know it's going to be a nonpolar covalent bond now let's look at the carbon hydrogen bond carbon is a non-metal and hydrogen is a non-metal so the fact that we have two nonmetals is a good indication that what we have is a covalent bond now to determine if it's polar or nonpolar because the elements are different we need to look at the electronegativity values carbon has an en value of 2.5 and the electronegativity value of hydrogen's 2.1 so the difference between 2.5 and 2.1 if he subtract him you should get point 4 which means that the carbon hydrogen bond is a nonpolar covalent bond now let's look at carbon and oxygen both of which are nonmetals so we know it's gonna be a covalent bond oxygen has an electronegativity value of 2.5 I mean that's carbon but oxygen is 3.5 so the electronegativity difference between these two atoms three point five minus two point five is 1.0 so 1.0 is greater than 0.5 so what we have here is a polar covalent bond as opposed to a nonpolar covalent bond now looking at the last example sodium fluoride sodium is a metal fluorine is a nonmetal so just by looking at that that's a good indication that what we have is an ionic bond now let's confirm it with the electronegativity values sodium has an en value of 0.49 and fluorine is 4.0 so the electronegativity difference between these two elements is 4 minus 0.9 which is 3.1 so this is definitely an ionic bond it exceeds the 1.9 value for ionic bonds number 2 which of the following bonds is most polar is it the nitrogen fluorine bond is it the phosphorus fluorine bond or the arsenic fluorine bond now grants it if we have access to the electronegativity table we can easily find the answer but how can you find it without using the e n values we need to do is look up the elements on a periodic table we have nitrogen below that is phosphorus and then arsenic and here's fluorine this is oxygen and this is carbon is gonna be over here now when two elements are very close to each other on a periodic table and the electronegativity difference will be small so it's not going to be very polar but when they're far apart and the electronegativity difference will be large and it's going to be polar so nitrogen is closest to fluorine so therefore the nitrogen fluorine bond is going to be the least polar arsenic is very far away from fluorine so we should expect that the arsenic fluorine bond will be the most polar and so this is gonna be the answer and that's how you can tell just look at the elements see which two elements are far apart as possible that's gonna be the bond that's most folding now this will only work if one element remains the same in each of the choices you're given if not you need to look at the electronegativity values so now let's look at the last example so here's carbon nitrogen oxygen and fluorine so we're comparing CF with NF and Oh F so oxygen is closest to fluorine so therefore the Oh F bond is going to be the least polar carbon is furthest away from fluorine so the CF bond is going to be the most polar so therefore this is the answer but let's confirm it so looking at the Oh F bond oxygen has an electronegativity value of 3.5 and for fluorine is 4.0 so the en difference for the Oh F bond is only 0.5 which means it's a polar covalent bond now nitrogen has an electronegativity value of 3.0 and comparing that to fluorine that's a difference of 1.0 so the nitrogen fluorine bond is also polar so that's another polar covalent bond carbon is 2.5 so the difference between these two values is 1.5 so as we can see the carbon fluorine bond is the most polar bond compared to the other options that are listed here but you don't need the e n values to figure this out just look for the two elements that are very far apart and that's gonna be the bond that is most polar