This X could be any atom. Now, we have bonds that are not all identical. In other words, we still have three of these ch bonds, but now we have a different CX bond. For example, if I replace this x with a chloride atom, so this is a chloride. That means the chloride, since the chloride is more electronegative than either the carbon or the H atoms, that means that chloride will pull electrons more strongly than either of the H atom. And so there will be an unequal electron density in this bond.