To draw the Lewis structure for the cyanate ion, OCN-, with two double bonds, we need to follow these steps:<\/p>\n\n\n\n
- \n
- Determine the total number of valence electrons<\/strong>:
- Oxygen (O) has 6 valence electrons.<\/li>
- Carbon (C) has 4 valence electrons.<\/li>
- Nitrogen (N) has 5 valence electrons.<\/li>
- The negative charge (\u20131) adds one more electron to the total.<\/li><\/ul>So, the total number of valence electrons is:
6+4+5+1=166 + 4 + 5 + 1 = 166+4+5+1=16 electrons.<\/li>\n\n\n\n - Arrange the atoms<\/strong>:
Carbon is usually the central atom in such a structure because it can form more bonds than nitrogen or oxygen. Thus, we place C in the middle, bonded to O and N.<\/li>\n\n\n\n- Draw the bonds<\/strong>:
Begin by placing a single bond between C and O, and another single bond between C and N. This uses up 4 electrons (2 electrons per bond).<\/li>\n\n\n\n- Distribute the remaining electrons<\/strong>:
You have 12 electrons left to distribute. Oxygen and nitrogen both require 8 electrons to complete their octets. Start by placing lone pairs on O and N to complete their octets:\n- \n
- Oxygen needs 6 more electrons to complete its octet.<\/li>\n\n\n\n
- Nitrogen needs 6 more electrons to complete its octet.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Form the double bonds<\/strong>:
Now, since you have 12 electrons left, you can form double bonds. Move a lone pair from oxygen to form a double bond with carbon, and another lone pair from nitrogen to form a double bond with carbon. This satisfies the octet rule for each atom.<\/li>\n\n\n\n- Assign formal charges<\/strong>:
Formal charge is calculated using the formula:
Formal\u00a0charge=(Valence\u00a0electrons)\u2212(Lone\u00a0pair\u00a0electrons)\u2212(Bonded\u00a0electrons\/2)\\text{Formal charge} = (\\text{Valence electrons}) – (\\text{Lone pair electrons}) – (\\text{Bonded electrons}\/2)Formal\u00a0charge=(Valence\u00a0electrons)\u2212(Lone\u00a0pair\u00a0electrons)\u2212(Bonded\u00a0electrons\/2) For each atom:\n- \n
- Oxygen<\/strong>: 6 valence electrons, 4 electrons from 2 bonds, 2 electrons from 1 lone pair. Formal charge = 6\u22124\u22122=06 – 4 – 2 = 06\u22124\u22122=0.<\/li>\n\n\n\n
- Carbon<\/strong>: 4 valence electrons, 4 electrons from 2 double bonds. Formal charge = 4\u22124\u22120=04 – 4 – 0 = 04\u22124\u22120=0.<\/li>\n\n\n\n
- Nitrogen<\/strong>: 5 valence electrons, 4 electrons from 2 bonds, 1 lone pair. Formal charge = 5\u22122\u22123=05 – 2 – 3 = 05\u22122\u22123=0.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
Thus, the formal charges on oxygen, carbon, and nitrogen are all 0.<\/p>\n\n\n\n
The correct answer is d. O = 0, C = 0, N = 0<\/strong>.<\/p>\n\n\n\n
Why this structure is correct:<\/h3>\n\n\n\n
- \n
- Each atom has a formal charge of 0, which is optimal for the structure’s stability.<\/li>\n\n\n\n
- The Lewis structure satisfies the octet rule for all atoms and uses the available electrons efficiently.<\/li>\n<\/ul>\n\n\n\n
![\"\"](\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/07\/learnexams-banner6-1166.jpeg\")
<\/figure>\n","protected":false},"excerpt":{"rendered":"Draw a Lewis structure for OCN- with 2 double bonds. What is the formal charge on each atom? a. O = -1 C = -1 N = +1 b. O = -1 C = 0 N = 0 c. O = 0 C = 0 N = -1 d. O = 0 C = 0 […]<\/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-261593","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/261593","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=261593"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/261593\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=261593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=261593"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=261593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Carbon<\/strong>: 4 valence electrons, 4 electrons from 2 double bonds. Formal charge = 4\u22124\u22120=04 – 4 – 0 = 04\u22124\u22120=0.<\/li>\n\n\n\n
- Assign formal charges<\/strong>:
- Draw the bonds<\/strong>: