That's where you are wrong. 3- H 2 is the most stable because it has the highest bond order (1), in comparison with the bond orders (1/2) of H 2 + and H 2-. Because the ground state is lower in energy, and thus is stabler than the excited state, whatever bond orders they have. 18 vertical columns. Dilithium (Li 2) O 2 + is more stable than O 2-.Because According to molecular orbital theory O 2 + has 15 electrons &it has one electron in antibonding orbital. Its negative ionic character suggests that it could be even less stable. Is a stable molecule with bond order is 3 and it is diamagnetic. New comments cannot be posted and votes cannot be cast. In other words, no bond can be sustained between two He atoms according to … Can You Describe the Smell of Ammonia to Me? With the help of molecular orbital theory show that Ne2 cannot exist as stable species . Polarity in water molecule and electronegativity of oxygen in that molecule. If the ball is only slightly pushed, it will settle back into its hollow, but a stronger push may start the ball rolling down the slope. However, antibonding effect of the excited antibonding orbital is weaker than the antibonding effect of the antibonding orbital in the ground state - so once the antibonding orbital gets excited, its overall effect on the molecule stability gets lower and the molecule becomes stable. Asked by Aashna Anith Kumar | 4th Feb, 2014, 11:50: PM. Be _valence shell configuration is 1s2 2s2. Be2+ and Be2- are both more stable than Be2. What is the bond order of He2? The σ 1s bonding and antibonding orbitals will be full. According to molecular orbital theory, He2 cannot exist as a stable diatomic molecule due to there being 2 bonding and 2 antibonding electrons. Answer. For a better experience, please enable JavaScript in your browser before proceeding. Noble Gas. e. Is stable molecule with bond order of 1 and it is diamagnetic save. Draw the molecular orbital diagram for each and explain your answer. b. Diprotons are not stable; this is due to spin-spin interactions in the nuclear force, and the Pauli exclusion principle, which forces the two protons to have anti-aligned spins and gives the diproton a binding energy greater than zero. Question starts telling you it IS the experimental fact, doesn't it? It has a higher energy, which is what makes the antibonding effect weaker. Noboru, the cat below, is the administrator of this unstable place. It can only exist at very low cryogenic temperatures. So, O 2 2+ is more stable than O 2 2- ion because of high bond order of O 2 2+ ion. In the periodic table, there are 18 groups i.e. Expert Answer: According to Molecular Orbital theory, only those molecule can exists which have net positive bond order while the molecules with negative or zero bond order will not exists. Eg: He + He; same mixing as above. If number of electrons more in antibonding orbital the molecule become unstable. Well, it doesn't say anything about configuration, but it tells us the molecule exist. The electron configuration of dihelium: If the molecule He2 were to exist, the 4s electrons would have to fully occupy both the bonding and antibonding levels, giving a bond order of zero. Click hereto get an answer to your question ️ Among H2 , He2^+ , Li2 , Be2 , B2 , C2 , N2 , O2^- , and F2 , the number of diamagnetic species is (Atomic numbers: H = 1 , … He2+: 3 valence → BO=1/2 → stable He2: 4 valence → BO=0 → unstable. 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Use the following MO diagram for Be2, Be2+, and Be2-. 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In physics, metastability is a stable state of a dynamical system other than the system's state of least energy.A ball resting in a hollow on a slope is a simple example of metastability. Since there are as many bonding electrons as as antibonding, there is no net bond. Never heard about it. Therefore, the 8 electrons would fill up both outer orbitals, the s and p orbitals, while for C2- it would only fill up the 1s orbital and have 2 electrons in the 2s orbital. Is unstable molecule with bond order of 1/2 and it is diamagnetic. Is there any additional information you can share with us? Postby Nhi Vo 3A » Tue Oct 25, 2016 7:08 pm, Postby Chem_Mod » Tue Oct 25, 2016 11:31 pm, Users browsing this forum: No registered users and 2 guests. This thread is archived. Therefore, He2 molecules are not predicted to be stable (and are not stable) in the lowest energy 4- Theoretically it would not be possible to form a molecule from two hydrides because the anti-bonding and bonding orbitals would cancel each other out. molecular orbital diagram of O 2 + Electronic configuration of O 2 + In the case of O 2-17 electrons are present &3 electrons are present in antibonding orbitals. a. Ga bc must have the possibility of averaging 4 valence electrons. 71% Upvoted. Please don't post links to copyrighted material, I have replaced it with a link to acs abstract. 3 comments. Please explain reasons. Since diatomic noble gas molecules, such as He2 and Ne2, do not exist. Although there is a bonding influence from the two bonding electrons, there is an antibonding influence from two antibonding electrons. To answer the question, you must construct a molecular orbital (MO) diagram for the hypothetical He 2 molecule. Diatomic Species by Molecular Orbital Theory. The substance emits high energy particles or rays from its unstable nucleus. The helium dimer is a van der Waals molecule with formula He 2 consisting of two helium atoms. , Using Standard Molar Entropies), Gibbs Free Energy Concepts and Calculations, Environment, Fossil Fuels, Alternative Fuels, Biological Examples (*DNA Structural Transitions, etc. All of the following can act as a semiconductor except The He H- system is isoelectronic with the He2 van der Waals molecule. c. Is unstable molecule with bond order of zero and it is diamagnetic. Suppose you're correct, then why would stabler excited He2 molecules, Because in the ground state the antibonding effect of the antibonding orbitals gets higher than in the excited molecule - and it gets high enough for the molecule to become unstable. The ground state MO electron configuration for He2 is (σ1s)2 (σ1s*)2 giving a bond order of 0. SaralStudy helps in prepare for NCERT CBSE solutions for Class 11th chemistry. Do you have any source for that? Which type of radiation emitted by radioactive nuclei is similar in mass to a helium atom? Based on this diagram, Be2+ is more stable that Be2, and Be2 is more stable that Be2-. Answer and Explanation: Di helium cation (He2+) possess three electron over all two are present in bonding sigma molecular orbital and are paired and one electron in antibonding sigma orbital which is unpaired. with this explanation, excited-state configuration (...) seems stabler than ground-state configuration (...) while it's not the case. On moving from group 1 to group 2 i.e. It was to my understanding that He2 = Helium Gas = what we used to put in party balloons? Be2- is more stable that Be2, and Be2 is more stable than Be2+. Be2 is more stable than either Be2- or Be2+. The electrons in antibonding orbitals cancel (and exceed) the stabilization resulting from electrons in bonding orbitals. The value of the bond order gives the number of electron pairs being shared between two atoms in a chemical bond. JavaScript is disabled. This chemical is the largest diatomic molecule—a molecule consisting of two atoms bonded together. Calculating the bond order results in 0. Therefore, C2- has a stronger bond as it is more stable and harder to pull an electron away from it. All of the following can act as a semiconductor except (a) Ga (b) Ge (c) Si (d) GaAs (e) GaN x2. Using molecular orbital theory, state why He2 not a stable molecule? share. But we are talking about molecule that is not a standard one - it has a filled antibonding oribtal, which makes is completely unstable in the ground state. How could Helium gas be nonexistent? Dihelium does not exist. report. To answer the question, you must construct a molecular orbital (MO) diagram for the hypothetical He, Register Alias and Password (Only available to students enrolled in Dr. Lavelle’s classes. A few years ago, this extremely weakly bonded system has been finally observed, although some controversies still remain on the inter- pretation of the experimental results [6]. So, the bond order is zero. hide. d. Is stable molecule with bond order of 3 and it is paramagnetic. Use molecular orbital theory to determine whether He2 or He2+ is more stable. Be2 is stable and paramagnetic, but Li2 is unstable. For a bond to be stable, the bond order must be a positive value. For a "standard" molecule - one that doesn't have filled antibonding orbital - that would be true. How to turn a weak acid into a strong acid. was last updated on 28th December 2020 Two electrons total, both occupy the sigma orbital, two more electrons in bonding than antibonding orbitals, the compound is stable. Two He atoms might then form a He2 molecule with configuration (σ1s)2(σ1s*)2 which is stabler than the two excited He atoms. 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