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Bend--> Bonds Electronegativity Differences Step 1- Is the bond Ionic or Covalent? This is a much better and easier way. It saves time and results in less chance of errors. metal (left side of the periodic table) to nonmetal (right side) = IONIC Nonmetal to nonmetal (both on the right side of the periodic table, H is a nonmetal)=Covalent
(Other way--> subtract the electronegativities. This is flawed. If >1.7 it is "mostly" IONIC, <1.7 is "mostly" covalent. (Several exceptions HF, BF3, BF2 in this flawed system.)
Step 2- What type of covalent bond do you have? So you know it is covalent. MY RULE If it is 2 of the same element bonded it is a NONPOLAR bond. If they are different it is a POLAR bond. (works 99% of the time).
***If and when you have to explain bond polarity, just state "there is a difference in electronegativities", or "there is no difference in electronegativities". Same element, same electronegativities=no difference. Different element, different electronegativity=difference. Bend--> Bonds Electronegativity Differences The other way-In the video To determine the polarity of a covalent bond using numerical means, the difference between the electronegativity of the atoms is taken. If the result is between 0.4 and 1.7 then, generally, the bond is polar covalent. This value 0.4 is arbitrary, close is good for an entry level chemistry course. So what does a Polar Covalent bond actually represent? Since there is a difference in electronegativities, one of the atom unequally shares the electrons (it hogs it), the probability of finding an electron is greater around the higher electronegative atom and thus becomes ever so slightly negative. The other atom becomes slightly positive. These have a partial charge (ions have full charges). We represent a partial charge with a lowercase Greek delta (d).
The arrow beneath the bond indicates the positive and points to the negative side. |
