To determine the bond order of the (\\text{B}_2^-) ion and whether it is paramagnetic or diamagnetic, let’s break it down step by step.<\/p>\n\n\n\n
Step 1: Molecular Orbital Theory and Electron Configuration<\/h3>\n\n\n\n
Molecular orbital theory helps us understand the bonding in molecules. For the (\\text{B}_2) molecule, the electron configuration is based on the combination of atomic orbitals from each boron atom.<\/p>\n\n\n\n
- \n
- Boron (B) has an atomic number of 5, which means it has 5 electrons. For two boron atoms, there are a total of 10 electrons.<\/li>\n\n\n\n
- The molecular orbitals for diatomic molecules like (\\text{B}_2) are filled in the following order (from lowest to highest energy):<\/li>\n\n\n\n
- (\\sigma_{1s}), (\\sigma^{1s}), (\\sigma{2s}), (\\sigma^<\/em>{2s}), (\\pi<\/em>{2p}), (\\pi^{2p}), (\\sigma{2p}), and (\\sigma^<\/em>_{2p}).<\/li>\n<\/ul>\n\n\n\n
The bonding and antibonding orbitals are filled as:<\/p>\n\n\n\n
- \n
- (\\sigma_{1s}) and (\\sigma^*_{1s}) (2 electrons in each, paired).<\/li>\n\n\n\n
- (\\sigma_{2s}) and (\\sigma^*_{2s}) (2 electrons in each, paired).<\/li>\n\n\n\n
- (\\pi_{2p}) (2 electrons, 1 in each (\\pi) orbital).<\/li>\n\n\n\n
- (\\pi^*_{2p}) (1 electron).<\/li>\n<\/ol>\n\n\n\n
For (\\text{B}_2^-), the negative charge means an additional electron, making it have 11 electrons in total.<\/p>\n\n\n\n
Step 2: Bond Order Calculation<\/h3>\n\n\n\n
The bond order is calculated using the formula:<\/p>\n\n\n\n
[
\\text{Bond order} = \\frac{1}{2} (\\text{Number of bonding electrons} – \\text{Number of antibonding electrons})
]<\/p>\n\n\n\nFor (\\text{B}_2^-), the electron configuration is:<\/p>\n\n\n\n
- \n
- Bonding electrons: (\\sigma_{1s}^2, \\sigma_{2s}^2, \\pi_{2p}^4) (8 electrons).<\/li>\n\n\n\n
- Antibonding electrons: (\\sigma^{2s}^2, \\pi^<\/em>{2p}^1) (3 electrons).<\/li>\n<\/ul>\n\n\n\n
Thus, the bond order is:<\/p>\n\n\n\n
[
\\text{Bond order} = \\frac{1}{2} (8 – 3) = \\frac{1}{2} (5) = 2.5
]<\/p>\n\n\n\nStep 3: Magnetic Properties<\/h3>\n\n\n\n
To determine whether (\\text{B}2^-) is paramagnetic or diamagnetic, we look at the electron configuration. Since there is an unpaired electron in the (\\pi^*<\/em>{2p}) orbital, (\\text{B}_2^-) is paramagnetic<\/strong>.<\/p>\n\n\n\n
Conclusion<\/h3>\n\n\n\n
- \n
- Bond order<\/strong> of (\\text{B}_2^-): 2.5<\/li>\n\n\n\n
- Magnetic properties<\/strong>: Paramagnetic<\/li>\n<\/ul>\n\n\n\n
Let me generate an image to visualize this molecular orbital diagram.<\/p>\n\n\n\n
Here is the molecular orbital diagram for the (\\text{B}2^-) ion, showing the electron configuration and the bond order calculation. As you can see, the ion has a bond order of 2.5, and since it has an unpaired electron in the antibonding (\\pi^*<\/em>{2p}) orbital, it is paramagnetic. Let me know if you need further explanations or adjustments!<\/p>\n\n\n\n
![\"\"](\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/02\/image-398.png\")
<\/figure>\n","protected":false},"excerpt":{"rendered":"What is the bond order of B2- ? is it paramagnetic or diamagnetic? The Correct Answer and Explanation is : To determine the bond order of the (\\text{B}_2^-) ion and whether it is paramagnetic or diamagnetic, let’s break it down step by step. Step 1: Molecular Orbital Theory and Electron Configuration Molecular orbital theory helps […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-190479","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/190479","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=190479"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/190479\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=190479"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=190479"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=190479"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Magnetic properties<\/strong>: Paramagnetic<\/li>\n<\/ul>\n\n\n\n
- Bond order<\/strong> of (\\text{B}_2^-): 2.5<\/li>\n\n\n\n