Those with positive bonding order are considered stable molecule while those with negative bond order or zero bond order are unstable molecule. Using molecular orbital theory; a) draw the MO diagrams for O2, O2+, and O2-. The molecular orbital diagram representing this order of energy levels is shown in fig. On the other hand, if there are unpaired electrons in the molecule, the substance is paramagnetic (attracted by the magnetic field). It is similar to constructive interference occurring in phase because of which electron probability density increases resulting in formation of bonding orbital. Magnetic character - If all the electrons in the molecule of a substance are paired, the substance is diamagnetic (repelled by the magnetic field). Bond order is inversely proportional to the bond length. b. there are two unpaired electrons in the MO electron configuration of O2 c. the energy … (ii) Calculate the pH value of 0.01M CH3 COOH if it is 5% dissociated. If value of bond order is positive, it indicates a stable molecule and if the value is negative or zero, it means that the molecule is unstable. Each horizontal line represents one orbital that can hold two electrons. A molecular orbital can hold two electrons, so both electrons in the H 2 molecule are in the σ 1s bonding orbital; the electron configuration is (σ 1 s) 2. Anti-Bonding Molecular Orbitals (ABMO) - Energy of Anti Bonding Molecular Orbitals is higher than Bonding Molecular Orbitals because the electron try to move away from the nuclei and are in repulsive state. No. Ans: The stabilities of these can be best explained using Molecular orbital theory. This is because _____. = (No. Accordingly, σ 2s and σ 2px have same symmetry and similarly for   σ *2s and σ *2px the energy of σ 2s is lowered and that of the σ 2px becomes higher. The molecular orbital theory (MO) has been introduced for the diatomic hydrogen molecules. According to the symmetry interactions, the two orbitals of the same symmetry repel each other and the lower energy orbital lowers down more while the higher energy orbital is energized more. 2 Formation of Bonding and Anti-Bonding Orbital. On the basis of this principle discuss the conditions for obtaining the maximum yield of SO3 in the following reaction. Formation of molecular orbitals occurs by the combination of atomic orbitals of proportional symmetry and comparable energy. Valence Bond Theory fails to answer certain questions like Why He2 molecule does not exist and why O2 is paramagnetic? The bond energies increase in the order: O22- < O2- < O2 < O2+. The electrons in the 1s Atomic Orbitals (AOs) of two atoms form two Molecular Orbitals (MOs) designated as s1s and s *1s.The 2s and 2p orbitals (eight AOs of two atoms) form four bonding MOs and four anti-bonding MOs as: Anti – Bonding MOσ: σ *2s, σ *2pz, π *2px, π *2py, Using Spectroscopy, the energy levels of these molecular orbitals are determined experimentally. The filling of molecular orbitals leaves 2 unpaired electrons in each of the π * (2p y) and π * (2p z) orbitals. Therefore, an electron in an atom may be described as occupying an atomic orbital, or by a wave function Ψ, which are solution to the Schrodinger wave equation. The greater the overlap, the more the bonding orbital is lowered and the anti-bonding orbital is raised in energy relative to AOs. We can calculate the bond order in the O 2 molecule by noting that there are eight valence electrons in bonding molecular orbitals and four valence electrons in antibonding molecular orbitals in the electron configuration of this molecule. Bond energy and bond order both increase with decreasing bond length. Consider two atoms A and B which have atomic orbitals described by the wave functions ΨA and ΨB .If electron cloud of these two atoms overlap, then the wave function for the molecule can be obtained by a linear combination of the atomic orbitals ΨA and ΨB i.e. Electrons may be considered either of particle or of wave nature. It is represented by s. When molecular orbital is formed by subtraction of wave function, the type of molecular orbitals formed are called Antibonding Molecular Orbitals and is represented byΨMO = ΨA - ΨB. No. The molecular orbitals formed by the combination of the atomic orbitals are shown in the center. no. According to Molecular Orbital Theory individual atoms combine to form molecular orbitals, as the electrons of an atom are present in various atomic orbitals and are associated with several nuclei. ( σ 1 s ) 2 . The two electrons in the hydrogen molecule may both be accommodated in the 1s g orbital if their spins are paired and the molecular orbital configuration for H 2 is 1s g 2. 2SO2(g)+ O2(g)⇌2SO3(g); ∆= - 42k.cal. This kind of energy reversal is due to mixing of 2s and 2p orbitals where the energy difference is very close, that is, for B, C, and N atoms. For example, homonuclear diatomic molecules of second row elements like Li2, Be2, B2 , C2, N2 , the σ 2pz  MOs is higher in energy than π 2px and π 2py MOs, σ1s, σ *1s, σ 2s, σ *2s, [π 2px = π 2py], σ 2pz [π *2px= π *2py], σ*2pz. BO = bonding orbitals ABO = Anti-bonding orbitals O 2: The electronic configuration of C 2 is K K (σ2s) 2 (σ * 2s) 2 n(2px) 2 n(2py) 2. Just as with atoms, we can write a molecular electron configuration for O2 σ2σ*2σ2π4π*2 We can also calculate the O–O bond order: BO 1 2 # bonding e# anti-bonding e  1 2 Register & Get Sample Papers solutions instantly. The molecular orbital configuration ofO2, O2-, O22-, O2+ are as follows:O2 = σ1s2, σ*1s2, σ2s2, σ*2s2, σ2pz2, π2px2 = π2py2,  π*2px1 = π*2py1Bond order = (10-6)/2 = 2, Number of unpaired electrons = 2, Therefore paramagnetic, O2- = σ 1s2, σ *1s2, σ 2s2, σ *2s2, σ 2pz2, π2px2 = π2py2, π*2px2 = π*2py1Bond order = (10-7)/2 = 1.5, Number of unπaired electrons = 1, Therefore paramagnetic, O22- = σ1s2, σ*1s2, σ2s2, σ*2s2, σ2pz2, π2px2 = π2py2, π*2px2 = π*2py2, Bond order = (10-8)/2 = 1, Number of unpaired electrons = 0, Therefore diamagnetic, O2+ = σ1s2, σ*1s2, σ2s2, σ*2s2, σ2pz2, π2px2 = π2py2, π*2px1= π*2py0, Bond order = (10-5)/2 = 2.5, Number of unpaired electrons = 1, Therefore paramagnetic. by subtraction or addition of wave functions of atomic orbitals, The above equation forms two molecular orbitals. The Lewis structure O=O does not accurately represent the diradical nature of molecular oxygen; molecular orbital theory must be used to adequately account for the unpaired electrons. Certain rules are to be followed while filling up molecular orbitals with electrons in order to write correct molecular configurations: Order of energy of various molecular orbitals is as follows: σ1s, σ *1s, σ 2s, σ *2s, σ 2pz, [π2px = π2py], [π*2px= π*2py], σ *2pz, Fig. This kind of mixing of orbitals or symmetry interaction is not applicable for O2 and F2 molecule formation because of larger energy gap between 2s and 2p orbitals for these atoms. They have higher energy than atomic orbitals. Complete List of Packages for Medical Preparation, Linear Combination of Atomic Orbital(LCAO), Difference between Atomic Orbitals and Molecular Orbitals, Order of Energies of Various Molecular Orbitals. Molecular orbital formed by addition of overlapping of two s orbitals shown in figure no. A molecular orbital diagram, or MO diagram, is a qualitative descriptive tool explaining chemical bonding in molecules in terms of molecular orbital theory in general and the linear combination of atomic orbitals (LCAO) method in particular. This is among the greatest successes of the molecular orbital theory. BMO has lower energy and hence greater stability than ABMO. Hence, the electronic configuration of the molecular orbitals accounts admirably for the paramagnetic properties of oxygen. For the second period elements, the 2s and 2p orbitals are important for MO considerations. For eac… c) determine which molecule has the strongest bond. Atomic orbitals are inherent property of an atom. Similarly, the energy of σ *2s lowered while that of σ *2px becomes higher. All rights reserved. The molecular orbital diagram for C 2 molecule is :. The Energies of Bonding Molecular Orbitals and Anti-Bonding Molecular Orbitals are shown in figure below: The factors upon which relative energies of molecular orbitals depend are: (i) Energies of the Atomic orbitals combining to form Molecular Orbitals. Greater the bond order, greater is the. The stability of a molecule is measured by its bond dissociation energy. Copyright © 2010-2019 www.emedicalprep.com. The bond order decreases in the order isO2+ >O2>O2->O22-so, we conclude stability is directly proportional to bond order. b) determine the bond order for all three molecules. When two oxygen atoms combines, the molecular orbital energy level diagram is as shown in the figure. The molecular orbital configuration of O 2 , O 2 - , O 2 2- , O 2 + are as follows: O 2 = σ1s 2 , σ*1s 2 , σ2s 2 , σ*2s 2 , σ2p z 2 , π2p x 2 = π2p y 2 , π*2p x 1 = π*2p y 1 Molecular orbital energy level diagram of N 2 molecule • Bond order = (8 2)/2 = 3 (N ≡ N) • Absence of unpaired electrons showed that N 2 molecule is diamagnetic. C) the energy of the π2p MOs is higher than that of the σ2p MO D) there are two unpaired electrons in the MO electron configuration of O2 … d) discuss the magnetic character of each molecule π2p and π*2p molecular orbitals originate from the 2py and 2pz atomic orbitals of the two oxygen atoms. An electron in atomic orbital is under the influence of only one positive nucleus of the atom. The electron configuration of O2+ is (σ2s)2(σ2s*)2(σ2p)2(π2p)4(π2p*)1. MOED of 'O 2 ' : Electronic configuration of Oxygen (Z = 8) is 1s 2 2s 2 2p 4. The unusual electron configuration prevents molecular oxygen from reacting directly with many other molecules, which are often in the singlet state. The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram (Figure 8). The number of unpaired electrons in O2+ and O22- is, respectively, 1 and 0. a. there are more electrons in the bonding orbitals than in the antibonding orbitals. Therefore in 1932 F. Hood and RS. Sol. The first photo is straight from a 2006 edition Pearson general chemistry textbook, and it shows you what the molecular orbital (MO) diagram for O2 is. On the basis of molecular orbital theory, select the most appropriate option. Bonding Molecular Orbitals (BMO) - Energy of Bonding Molecular Orbitals is less than that of Anti Bonding Molecular Orbitals because the attraction of both the nuclei for both the electron (of the combining atom) is increased. Dashed lines show which of the atomic orbitals combine to form the molecular orbitals. But experimental evidence for some diatomic molecules have shown that the above sequence of energy levels of MOs is not correct for all the molecules. Mulliken came up with theory known as Molecular Orbital Theory to explain questions like above. soo, you can verify the below link for any further clarifiaction and also for ur answer of the molecular orbit configuration for peroxide ion Molecular Orbital Theory O2– – = σ1s2,σ*1s2,σ2s2,σ*2s2,σ2px2, π2py2= π2pz2,π*2py2=π*2pz2,σ*2px0. Answer. 6 Order of Energy for O2 and Higher molecules, σ 1s, σ *1s, σ 2s, σ *2s, [π 2px = π 2py], σ 2px [π *2px= π *2py], σ*2pz, Fig. Thus, the bond order is two. (i) Formation Oxygen molecule: Electronic configuration of oxygen atom-1s² 2s² 2p⁴ Atomic orbitals of oxygen combine to form molecular orbitals. 2. Although the Lewis structure and molecular orbital models of oxygen yield the same bond order, there is an important difference between these models. They have lower energy than atomic orbitals involved. The electron configurations are shown below where we have 16 electrons to … An electron Molecular orbital is under the influence of two or more nuclei depending upon the number of atoms present in the molecule. Electronic configuration of oxygen = 1s 2 2s 2 2p 4. A) the bond order in O2 can be shown to be equal to 2. Molecular Orbital formed by subtraction of overlapping of two s orbitals are shown in figure no. The bond length in the oxygen species can be explained by the positions of the electrons in molecular orbital theory. 27) Molecular Orbital theory correctly predicts paramagnetism of oxygen gas, O2. From the diagram, the molecular electronic configuration of oxygen is. Molecular Orbital theory correctly predicts paramagnetism of oxygen gas, O2. 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