The F-F bond in F₂ is relatively weak because the lone pairs of electrons on one F atom repel the lone pairs on the other F atom; K_p = 7.83 at 1500 K for the reaction F₂(g) ⇌ 2 F(g). (c) Why is the F-F bond in F₂ weaker than the Cl-Cl bond in Cl₂?

Video transcript

welcome back everyone in the bonds formed, the lone pairs of electrons on one atom repel the lone pair of electrons on the other atom in the bond. Consider the following di atomic species we have flooring with a bond energy of 155 kg per mole chlorine. With a bond energy of 242 kg per mole brimming with a bond energy of 1 93 kg per mole. And I dane with a bond energy of 151 kg per mole. Why is the bond energy of flooring smaller than expected? So we're going to first recall that bond length follows the trend for atomic radius on our periodic table. And we want to recall that on our periodic table. Atomic radius is increasing towards the bottom left of our periodic tables. So we would recognize that in Group seven A. Which is our halogen group. We have our atom flooring, chlorine, bromine and iodine across period four or sorry, period five is where iodine is located. And because of its position, we would recognize that florian has the smallest radius and so as far as our ranking for the radius florian would be the smallest where chlorine is next with a larger radius bromine comes after chlorine and then iodine would have the largest radius. But let's go ahead and label flooring as again the smallest atomic radius, which therefore allows us to conclude that it has a or the shortest bond length. So with this in mind, that is why we would expect it to have a hi bond energy since the bond is so short. However, we want to recognize that florin is one of the most electro negative elements on the periodic table. So it's the most electro negative element. And because florian is the most election negative element and a halogen making it a di atomic molecule, we're going to have to flooring atoms bonded to one another. Where in this bond, our loan electrons making up this bond, which would be to are going to have great repulsion from one another. So they barely want to be bonded and they're going to want to move closer to each individual florian atom, meaning that due to this great repulsion of these electrons, we would therefore say that our flooring flooring single bond is a weaker bond. And therefore we can conclude that our bond energy of flooring is going to be smaller than what we would expect. So that means that with what we've outlined, the only correct choice to confirm what we've outlined is going to be Choice B. Which states that the bond energy of flooring is smaller than expected because it's smaller in size, leading to a greater repulsion between the lone pairs in the flooring atoms B would be our final answer. I hope everything I reviewed was clear. If you have any questions, please leave them down below and I'll see everyone in the next practice video