[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-657128-en":3,"doc-seo-657128-105":31,"detail-sidebar-cat-0-en-105":98},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":21,"is_downloadable":21,"audit_status":21,"page_count":22,"language":23,"language_code":24,"site_id":25,"html_lang":24,"table_of_contents":26,"faqs":27,"seo_title":28,"seo_description":14,"update_tm":29,"read_time":30},657128,962093532725,"GGG","https://ap-avatar.wpscdn.com/davatar_276721f389ce27ea32af1340a28f341c",8,"Research & Report","THE STRUCTURE OF MOLECULES - AN EXPERIMENT USING MOLECULAR MODELS","Explains how molecular structure can be modeled and understood through key historical ideas and electron-based bonding concepts. Discusses Kekulé’s tetratomic view of carbon, the tetrahedral arrangement proposed by van ’t Hoff and Le Bel, and Lewis’s electron and octet rule framework. Shows how Lewis structures represent bonding and nonbonding electron pairs, electron counting conventions, valence electrons, and why molecules like H2O follow tetrahedral electron geometry while compounds with “electron shortage” form double bonds.","THE STRUCTURE OF MOLECULES AN EXPERIMENT USING MOLECULAR MODELS  \n©2009 by David A. Katz. All rights reserved.  \nIn a footnot to a 1857 paper, Friedrich August Kekulé suggested that carbon was tetratomic, that is, carbon has a valence of 4. In 1858, Kelkulé stated  \n“When the simplest compounds of this element are considered (marsh gas, methyl chloride, chloride of carbon, chloroform, carbonic acid, phosgene, sulphide of carbon, hydrocyanic acid, etc.) it is seen that the quantity of carbon which chemists have recognized as the smallest possible, that is, as an atom, always unites with 4 atoms of a monoatomic or with 2 atoms of adiatomic element; that in general the sum of the chemical units of the elements united with one atom of carbon is 4. This leads us to the view that carbon is tetratomic or tetrabasic.  \nIn the cases of substances which contain several atoms of carbon, it must be assumed that at least some of that atoms are in the same way held in the compound by the affinity of carbon, and the carbon atoms attach themselves to one another,  ”  \nAs early as 1870, graphic formulas of carbon compounds were drawn as shown:  \nMethane  \nH  \n׀  \nH–C–H  \n׀  \nH  \nethylene  \nH H  \n׀ ׀  \nC = C  \n׀ ׀  \nH H  \nThese drawings imply that the atom-atom linkages, indicated by valence strokes, lie in plane.  \nIn 1874, Jacobus Henricus van 't Hoff and Joseph Achille LeBel, independently, proposed that the four bonds of carbon were arranged three dimensionally, pointed toward the corners of a tetrahedron. The tetrahedral carbon atom is sometimes referred to as the Van't Hoff-Le Bel theory. The threedimensional structure of methane can be represented by a diagram known as a Fischer projection:  \nThe physical significance of the chemical linkages between atoms, expressed by the lines or valence strokes in molecular structure diagrams, became evident soon after the discovery of the electron. In 1916 in a classic paper, G. N. Lewis suggested, on the basis of chemical evidence, that the single bonds in graphic formulas involve two electrons and that an atom tends to hold eight electrons in its outermost or valence shell.  \nLewis' proposal that atoms generally have eight electrons in their outer shells is known as the octet rule. It can be applied to many atoms, but is particularly important in the treatment of covalent compounds of atoms in the second and third rows of the Periodic Table. For atoms such as carbon, oxygen, nitrogen, and fluorine, the eight valence electrons occur in pairs that occupy tetrahedral positions around the central atom core. Some of the electron pairs do not participate directly in chemical bonding and are called unshared or nonbonding pairs; however, the structures of compounds containing such unshared pairs reflect the tetrahedral arrangement of the four pairs of valence shell electrons. In the H2O molecule, which obeys the octet rule, the four pairs of electrons around the central oxygen atom occupy essentially tetrahedral positions; there are two unshared nonbonding pairs and two bonding pairs that are shared by the O atom and the two H atoms . The H—O—H bond angle is nearly but not exactly tetrahedral since the properties of shared and unshared pairs of electrons are not exactly alike.  \nEssentially, all organic molecules obey the octet rule, and so do most inorganic molecules and ions. For species that obey the octet rule it is possible to draw electron-dot, or Lewis, structures . The drawing of the H2 O molecule, above, is an example of a Lewis structure.  \nIn a Lewis structure there are eight electrons around each atom (except for H atoms, which always have two electrons) Group 2A atoms which form 2 bonds have 4 electrons and Group 3A atoms which form 3 bonds have 6 electrons.  \nThere are two electrons in each bond (designated by a line) .  \nWhen counting electrons in these structures, one considers the electrons in a bond between two atoms as belonging to the atom under consideration . Thus, electrons may be c","cbCaid4zoO0ZTdek","https://ap.wps.com/l/cbCaid4zoO0ZTdek","pdf",164733,4,1,12,"English","en",105,"# The structure of molecules\n## Kekulé’s tetratomic concept of carbon\n## Tetrahedral bonding: van ’t Hoff and Le Bel\n## Electron discovery and the Lewis model\n## Octet rule and Lewis structures\n## Electron counting and bonding geometry\n## Double bonds when octet structures are insufficient","[{\"question\":\"What did Kekulé propose about carbon’s bonding?\",\"answer\":\"Kekulé suggested carbon is tetratomic, meaning carbon typically unites with four atoms (valence 4) in chemical compounds.\"},{\"question\":\"How did van ’t Hoff and Le Bel explain the geometry of carbon bonds?\",\"answer\":\"They independently proposed that carbon’s four bonds are arranged three-dimensionally, pointing toward the corners of a tetrahedron.\"},{\"question\":\"What is the octet rule and how is it used in Lewis structures?\",\"answer\":\"The octet rule states that atoms tend to have eight electrons in their valence shell. Lewis structures map bonding and nonbonding electron pairs so that (with key exceptions like hydrogen) each atom achieves an octet.\"}]","THE STRUCTURE OF MOLECULES - AN EXPERIMENT USING MOLECULAR MODELS | PDF",1792974528,30,{"code":4,"msg":32,"data":33},"ok",{"site_id":25,"language":24,"slug":34,"title":13,"keywords":35,"description":14,"schema_data":36,"social_meta":92,"head_meta":94,"extra_data":96,"updated_unix":97},"the-structure-of-molecules-an-experiment-using-molecular-models","",{"@graph":37,"@context":91},[38,54,74],{"@type":39,"itemListElement":40},"BreadcrumbList",[41,45,49,52],{"item":42,"name":43,"@type":44,"position":21},"https://docshare.wps.com","Home","ListItem",{"item":46,"name":47,"@type":44,"position":48},"https://docshare.wps.com/document/","Document",2,{"item":50,"name":12,"@type":44,"position":51},"https://docshare.wps.com/document/research-report/",3,{"item":53,"name":13,"@type":44,"position":20},"https://docshare.wps.com/document/the-structure-of-molecules-an-experiment-using-molecular-models/657128/",{"url":53,"name":13,"@type":55,"image":56,"author":61,"headline":13,"publisher":63,"fileFormat":66,"inLanguage":24,"description":14,"dateModified":67,"datePublished":68,"encodingFormat":66,"isAccessibleForFree":69,"interactionStatistic":70},"DigitalDocument",{"url":57,"@type":58,"width":59,"height":60},"https://docshare.wps.com/thumbnails/the-structure-of-molecules-an-experiment-using-molecular-models/657128.png","ImageObject",300,407,{"name":9,"@type":62},"Person",{"url":42,"name":64,"@type":65},"DocShare","Organization","application/pdf","2026-10-29","2026-10-26",true,{"@type":71,"interactionType":72,"userInteractionCount":20},"InteractionCounter",{"@type":73},"ViewAction",{"@type":75,"mainEntity":76},"FAQPage",[77,83,87],{"name":78,"@type":79,"acceptedAnswer":80},"What did Kekulé propose about carbon’s bonding?","Question",{"text":81,"@type":82},"Kekulé suggested carbon is tetratomic, meaning carbon typically unites with four atoms (valence 4) in chemical compounds.","Answer",{"name":84,"@type":79,"acceptedAnswer":85},"How did van ’t Hoff and Le Bel explain the geometry of carbon bonds?",{"text":86,"@type":82},"They independently proposed that carbon’s four bonds are arranged three-dimensionally, pointing toward the corners of a tetrahedron.",{"name":88,"@type":79,"acceptedAnswer":89},"What is the octet rule and how is it used in Lewis structures?",{"text":90,"@type":82},"The octet rule states that atoms tend to have eight electrons in their valence shell. Lewis structures map bonding and nonbonding electron pairs so that (with key exceptions like hydrogen) each atom achieves an octet.","https://schema.org",{"og:url":53,"og:type":93,"og:title":13,"og:site_name":64,"og:description":14},"article",{"robots":95,"canonical":53},"index,follow",{"doc_id":7,"site_id":25},1793029522,{"code":4,"msg":5,"data":99},[100,104,108,112,117,122,127,129,134,137,141],{"id":21,"doc_module":4,"doc_module_name":47,"category_name":101,"show_sort_weight":102,"slug":103},"Story & Novel",90,"story-novel",{"id":48,"doc_module":4,"doc_module_name":47,"category_name":105,"show_sort_weight":106,"slug":107},"Literature",80,"literature",{"id":20,"doc_module":4,"doc_module_name":47,"category_name":109,"show_sort_weight":110,"slug":111},"Exam",70,"exam",{"id":113,"doc_module":4,"doc_module_name":47,"category_name":114,"show_sort_weight":115,"slug":116},5,"Comic",60,"comic",{"id":118,"doc_module":4,"doc_module_name":47,"category_name":119,"show_sort_weight":120,"slug":121},6,"Technology",50,"technology",{"id":123,"doc_module":4,"doc_module_name":47,"category_name":124,"show_sort_weight":125,"slug":126},7,"Healthcare",40,"healthcare",{"id":11,"doc_module":4,"doc_module_name":47,"category_name":12,"show_sort_weight":30,"slug":128},"research-report",{"id":130,"doc_module":4,"doc_module_name":47,"category_name":131,"show_sort_weight":132,"slug":133},9,"Religion & Spirituality",20,"religion-spirituality",{"id":132,"doc_module":4,"doc_module_name":47,"category_name":135,"show_sort_weight":132,"slug":136},"World Cup","world-cup",{"id":138,"doc_module":4,"doc_module_name":47,"category_name":139,"show_sort_weight":138,"slug":140},10,"Lifestyle","lifestyle",{"id":142,"doc_module":4,"doc_module_name":47,"category_name":143,"show_sort_weight":113,"slug":144},19,"General","general"]