The first is for all molecules except for `O_2` and `F_2`. Unfortunately, MO Theory can be the most difficult to understand and visualize, which is why we covered the other two first. The electronic configuration of N2 is KK (σ(2s))2  (σ∗(2s))2  (π(2px))2  (π(2py))2  (σ(2pz))2. bond order is positive. In the `pi^"*"` orbitals, the two electrons are unpaired. That's it for the MO diagram of `B_2`! Your email address will not be published. According to MO theory, when two atomic orbitals interact, they form one bonding orbital and one antibonding orbital. Electronic configuration of C2 = (σ2s) 2 (σ * 2s) 2 n (2px) 2 n (2py) 2. Electrons in bonding orbitals will strengthen the bonds of the molecule. Let's calculate the bond order of `"Ne"_2`. These states are often written as `+` and `-`, or drawn as different colors. In MO theory, electrons in bonding orbitals promote bonding whereas electrons in anti-bonding orbitals weaken bonds. In a diatomic molecule such as O2 O 2, the bond order simply tells the number of bonds between the two atoms. The reason bleach removes color is that it removes double bonds, thereby eliminating the `pi` to `pi^"*"` transition. No bond is formed between two helium therefore He2 does not exist. The answer to this question requires more understanding of orbital behavior than we previously have. The bond order is therefore: This is in line with how we expect noble gases to behave! Bond order value of 3 means that N2 contains a triple bond. If the molecules has some unpaired electrons ,it is paramagnetic in nature. Paramagnetic: when unpaired electrons exist. As we mentioned in earlier posts, the way we determined the shape of orbitals is through Schrodinger's wave equation. When oxygen gas is poured in between two magnets, the gas is attracted to the magnets. 3) One unpaired electron is present.Hence it is paramagnetic. Whenever two orbitals interact to form molecular orbitals, they form a set of two molecular orbitals: one bonding orbital and one antibonding orbital. In a diatomic molecule such as `O_2`, the bond order simply tells the number of bonds between the two atoms. Boron has 2 electrons in the `2s` orbitals and 1 electron in the `2p` orbital. Make sure you're using the correct MO diagram! The MO diagram has `6` electrons as well. 4) Nature of bond in terms of bond order : Bond order 1 ,2 and 3 mean single ,double and triple bond. The graphical representation presented in Fig. Figure A partial molecular orbital energy-level diagram for the HF molecule. Your email address will not be published. Aufbau Principle: electrons will always fill the orbitals from bottom to top. This applies primarily to the `pi` and `pi^"*"` orbitals, where one electron will go into each orbital before filling in the second. = 8 − 2 2 = 3 Here’s a guide on how to construct MO diagrams, in case you need help. When two s-orbitals of the opposite sign interact, they form a `sigma"-antibonding"` orbital. Notice that the last two electrons go into two separate `pi` orbitals instead of filling 2 electrons into one orbital. 7. Here's how they apply: 1. With two p-orbitals along the same orientation, there are two possibilities. Diamagnetic molecules are molecules that exhibit no magnetic properties due to the lack of unpaired electrons. 2) Stability of molecules in terms of bond order. Recall that, when atoms absorb energy, they absorb a specific wavelength of energy. Each orbital can hold two electrons, so orbitals lower should always fill up before the orbitals higher up are filled. After all, MO theory is one of the most complicated sections covered in general chemistry. The MO diagram will be the same as the MO diagram of `O_2`, except with `1` less electron. The electronic configuration of Be2 is KK  (σ(2s))2  (σ∗(2s))2, The electronic configuration of B2 is KK (σ(2s))2  (σ∗(2s))2  π(2px)1  π(2py)1, The electronic configuration of C2 is KK (σ(2s))2  (σ∗(2s))2  (π(2px))2  (π(2py))2. The short and simple (perhaps unsatisfying) answer is that `F_2` and `O_2` are so electronegative that they "pull" the `sigma_"2p"` orbital closer to them. Hund's Rule: orbitals on the same energy level will fill singly before doubly. There are two MO diagrams we need to learn for these elements. Why is it that, if magnetism results from unpaired electrons, that `O_2` is magnetic? Apologies for the binder paper, I ran out of printer paper. 6. A molecule with the bond order of 3 is more stable than a molecule with bond order of 2 and so on. 3)It has no unpaired electron ,it should be diamagnetic. MO diagrams allow us to view the specific configuration of valence electrons in their molecular orbitals. `O_2` is comprised of two `O` atoms, so it has `2(6)=12` valence electrons. 3. This very slight difference becomes profoundly important when it comes to the behavior of `O_2` and `F_2`. Chapter.plz send me tha note. When p-orbitals with the same sign and orientation interact, they form a `pi`-bond: On the other hand, when the p-orbitals are oriented with opposite signs, they form a `pi^"*"`- bond, pronounced  "`pi`-antibonding.".