[{"data":1,"prerenderedAt":114},["ShallowReactive",2],{"cheatsheet-chemical-bonding-and-lewis-structures":3},{"sheet":4},{"sheetSlug":5,"topicSlugs":6,"primaryTopic":7,"title":8,"subtitle":9,"sections":10},"chemical-bonding-and-lewis-structures",[5],14,"Chemical Bonding & Lewis Structures","Valence counting, the octet rule, drawing structures, formal charge, exceptions, and resonance.",[11,23,31,40,48,57,65,74,82,90,98,106],{"heading":12,"kind":13,"items":14},"Count valence electrons","rules",[15],{"ref":16,"mode":19,"provenance":20,"text":21,"source_hash":22},{"type":17,"topic":7,"id":18,"field":17},"rule","LB-R001","transform","owned_workbook","Total = sum of each atom's valence electrons (main-group group number: H 1, B 3, C/Si 4, N/P 5, O/S 6, halogens 7) + 1 per negative charge − 1 per positive charge. The finished structure must use exactly this many.","16ad1a44acb608dcb2d5f9f108cb8036552d6a36bc4eea90c2918ed816f021be",{"heading":24,"kind":13,"items":25},"Octet (duet for H)",[26],{"ref":27,"mode":19,"provenance":20,"text":29,"source_hash":30},{"type":17,"topic":7,"id":28,"field":17},"LB-R002","Atoms aim for 8 valence electrons (H for 2). A bonding pair counts toward BOTH bonded atoms; a lone pair counts only for its own atom.","4e457264a4032ba085585896018ac9cf86261ced4d9d1ca49cc22efccd73a481",{"heading":32,"kind":13,"items":33},"Pick the central atom",[34],{"ref":35,"mode":19,"provenance":37,"text":38,"source_hash":39},{"type":17,"topic":7,"id":36,"field":17},"LB-R003","original","Central atom = usually the lowest-electronegativity atom. H is always terminal; F almost always terminal; C is central with H/N/O/halogens (CO₂ → C; H₂O → O; SiO₂ → Si).","1551b6a8f545f01a115f8f2fe400554bfdcae705f1ac12631388612d99767e7f",{"heading":41,"kind":13,"items":42},"Bonds & multiple bonds",[43],{"ref":44,"mode":19,"provenance":20,"text":46,"source_hash":47},{"type":17,"topic":7,"id":45,"field":17},"LB-R004","Single = 1 shared pair, double = 2, triple = 3. If the central atom is short of an octet, convert a terminal lone pair into a shared pair. A double/triple bond is still ONE bond domain per atom.","eaadfb44bc72be568af18e47fdc534efe039547cda2f60ab971dae1feeacec8c",{"heading":49,"kind":50,"items":51},"Distribute the electrons","steps",[52],{"ref":53,"mode":19,"provenance":20,"text":55,"source_hash":56},{"type":17,"topic":7,"id":54,"field":17},"LB-R005","(1) Complete terminal octets first (terminal halogen/O gets 3 lone pairs). (2) Put leftovers on the central atom. (3) If a period-2 central atom is still short, make a multiple bond; period-3+ may keep the extra as a lone pair.","8991d959f93c36056518e7c17c9fb0753069ad9dae3344f7b111df65f7b1c50b",{"heading":58,"kind":13,"items":59},"Verify the count",[60],{"ref":61,"mode":19,"provenance":20,"text":63,"source_hash":64},{"type":17,"topic":7,"id":62,"field":17},"LB-R006","Add it back: 2 e⁻ per single bond, 4 per double, 6 per triple, 2 per lone pair, 1 per radical. The sum must equal the valence total you started with.","e2f6bfc37f3f22ea6e11be8a558ae2cf33381c037e02df6f87a4af8a25149440",{"heading":66,"kind":67,"items":68},"Incomplete octets","pitfalls",[69],{"ref":70,"mode":19,"provenance":37,"text":72,"source_hash":73},{"type":17,"topic":7,"id":71,"field":17},"LB-R007","Be and B can be stable with fewer than 8: Be has 4 in BeCl₂, B has 6 in BF₃: not enough electrons, and no terminal lone pair worth converting.","a39c08f62e11b6396c32120a4b14e05f87bbb8f1ffa50af08dec85eeeeac248c",{"heading":75,"kind":67,"items":76},"Odd-electron radicals",[77],{"ref":78,"mode":19,"provenance":37,"text":80,"source_hash":81},{"type":17,"topic":7,"id":79,"field":17},"LB-R008","An odd valence total (NO 11, NO₂ 17, ClO₂ 19) cannot fully pair, so one atom carries a lone unpaired electron, on the central/less-electronegative atom. That atom is one short of an octet, and that is correct.","e9ef76db5984af4414c0cc881b7ed21b4cdb2cf355d38aaba967c74b116b3001",{"heading":83,"kind":13,"items":84},"Expanded octets (hypervalent)",[85],{"ref":86,"mode":19,"provenance":37,"text":88,"source_hash":89},{"type":17,"topic":7,"id":87,"field":17},"LB-R009","Period-3+ central atoms (P, S, Cl, Br, I, Xe) can be drawn past an octet: PCl₅ (10), SF₆ (12), also BrF₅, XeF₄. Period-2 atoms (B, C, N, O, F) never exceed 8. Modern models credit delocalized / 3-centre-4-electron bonding, not d-orbital expansion.","8d976719f32e5dd68362e8d27aa54bbee00fc9552c2f8f95a7045c70e75cbd8f",{"heading":91,"kind":13,"items":92},"Formal charge",[93],{"ref":94,"mode":19,"provenance":20,"text":96,"source_hash":97},{"type":17,"topic":7,"id":95,"field":17},"LB-R011","FC = valence electrons − nonbonding electrons − (bonding electrons / 2). Equivalently: valence − lone-pair electrons − number of bonds. Sum of all FCs = the species charge (0 for a neutral molecule).","de7565cca3047c6d29da1975bf4947cc8462518c7ca2bdca14830683812005a6",{"heading":99,"kind":13,"items":100},"Best structure by formal charge",[101],{"ref":102,"mode":19,"provenance":20,"text":104,"source_hash":105},{"type":17,"topic":7,"id":103,"field":17},"LB-R013","Prefer: fewest nonzero formal charges; then smallest magnitudes; then negative FC on the more electronegative atom; avoid like charges on adjacent atoms. It is a guideline; defer to species-specific convention when both forms are valid.","d4db20ee0828c31e5018e9711b9c11f91d144b7bb89fece31cfa80a15fd09015",{"heading":107,"kind":13,"items":108},"Resonance",[109],{"ref":110,"mode":19,"provenance":20,"text":112,"source_hash":113},{"type":17,"topic":7,"id":111,"field":17},"LB-R014","Resonance forms share atom positions and electron count, differing only in π-bond / lone-pair placement (σ bonds never break). Move a π bond to a lone pair on one side while promoting a lone pair to a π bond on the other; link with ↔.","eea15334f80722d8d8dd3de27bc8687ba5647e4c58f5ac7a26b0081ba9c3fca5",1787246033034]