https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:chemical-bonding/x2613d8165d88df5e:ionic-bonds/v/valence-electrons-and-ionic-compounds 2022-09-07T08:21:01.673602243Z Valence electrons and ionic compounds When forming ions, elements typically gain or lose the minimum number of electrons necessary to achieve a full octet. For example, fluorine has seven valence electrons, so it is most likely to gain one electron to form an ion with a 1- charge. We can use this method to predict the charges of ions in ionic compounds. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/0fa65651-5c25-4356-ab62-0ddbdaf7cdb5_1280_720_base.png Valence electrons and ionic compounds When forming ions, elements typically gain or lose the minimum number of electrons necessary to achieve a full octet. For example, fluorine has seven valence electrons, so it is most likely to gain one electron to form an ion with a 1- charge. We can use this method to predict the charges of ions in ionic compounds. https://cdn.kastatic.org/ka-youtube-converted/XPnlIEk7XrU.mp4/XPnlIEk7XrU.mp4 475 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:molecular-and-ionic-compound-structure-and-properties/x2eef969c74e0d802:lewis-diagrams/v/drawing-lewis-diagrams 2022-09-07T08:21:01.673602243Z Drawing Lewis diagrams A Lewis diagram shows how the valence electrons are distributed around the atoms in a molecule. Shared pairs of electrons are drawn as lines between atoms, while lone pairs of electrons are drawn as dots next to atoms. When constructing a Lewis diagram, keep in mind the octet rule, which refers to the tendency of atoms to gain, lose, or share electrons until they are surrounded by eight valence electrons (an octet). Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/70da601e-6fd0-45f2-8dcf-865ecb21e47e_1280_720_base.png Drawing Lewis diagrams A Lewis diagram shows how the valence electrons are distributed around the atoms in a molecule. Shared pairs of electrons are drawn as lines between atoms, while lone pairs of electrons are drawn as dots next to atoms. When constructing a Lewis diagram, keep in mind the octet rule, which refers to the tendency of atoms to gain, lose, or share electrons until they are surrounded by eight valence electrons (an octet). https://cdn.kastatic.org/ka-youtube-converted/9BZFphoY-vo.mp4/9BZFphoY-vo.mp4 428 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/organic-chemistry/gen-chem-review/dot-strcutures-jay/v/dot-structures-i-single-bonds-1 2021-03-23T09:46:01Z Dot structures I: Single bonds How to draw single bonds using dots to represent valence electrons. Jay video https://cdn.kastatic.org/googleusercontent/PqnGBMwbtZTuieBeZ_8ei6NYkXzT448fHcsTCt0DUyDz6QxvzPuMu_m_qxRuLsG-W6avRH2aTVyNkFepOQ4UBgNu Dot structures I: Single bonds How to draw single bonds using dots to represent valence electrons. https://cdn.kastatic.org/ka-youtube-converted/BIZNBfBuu1w.mp4/BIZNBfBuu1w.mp4 417 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/organic-chemistry/gen-chem-review/dot-strcutures-jay/v/dot-structures-ii-multiple-bonds-1 2021-03-22T03:07:32Z Dot structures II: Multiple bonds How to draw double and triple bonds using dots to represent valence electrons. Jay video https://cdn.kastatic.org/googleusercontent/EH6iVAnuJGvq_GVcqyviOu11WQfLZXuh2dFJF7R26bfxsMsk0tvElR2WmRhToK0vD9kbsOfzaVGDwP2DyCrWRVf9 Dot structures II: Multiple bonds How to draw double and triple bonds using dots to represent valence electrons. https://cdn.kastatic.org/ka-youtube-converted/WLGTx6sSIOc.mp4/WLGTx6sSIOc.mp4 359 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:molecular-and-ionic-compound-structure-and-properties/x2eef969c74e0d802:lewis-diagrams/v/worked-example-lewis-diagram-of-cyanide-ion 2022-09-15T10:37:14.07019524Z Worked example: Lewis diagram of the cyanide ion (CN⁻) We can draw Lewis structures for polyatomic ions (ions containing multiple atoms) using the same stepwise procedure as for neutral molecules. In this video, we'll see how to construct the Lewis diagram of the cyanide ion (CN⁻). Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/70984491-1a0f-4b1b-94dd-5bc3e1ed53ca_1280_720_base.png Worked example: Lewis diagram of the cyanide ion (CN⁻) We can draw Lewis structures for polyatomic ions (ions containing multiple atoms) using the same stepwise procedure as for neutral molecules. In this video, we'll see how to construct the Lewis diagram of the cyanide ion (CN⁻). https://cdn.kastatic.org/ka-youtube-converted/Y8p4cthWB8I.mp4/Y8p4cthWB8I.mp4 268 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:molecular-and-ionic-compound-structure-and-properties/x2eef969c74e0d802:lewis-diagrams/v/worked-example-lewis-diagram-of-formaldehyde 2022-09-15T10:37:14.07019524Z Worked example: Lewis diagram of formaldehyde (CH₂O) The Lewis diagram of a molecule can be constructed using the following stepwise procedure: (1) Find the number of valence electrons in the molecule. (2) Draw single bonds between bonded atoms. (3) Distribute the remaining electrons throughout the molecule, keeping in mind the duet and octet rules. In this video, we'll use these steps to construct the Lewis diagram of formaldehyde (CH₂O). Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/213a0068-5e27-4419-850d-c42a1d28c284_1280_720_base.png Worked example: Lewis diagram of formaldehyde (CH₂O) The Lewis diagram of a molecule can be constructed using the following stepwise procedure: (1) Find the number of valence electrons in the molecule. (2) Draw single bonds between bonded atoms. (3) Distribute the remaining electrons throughout the molecule, keeping in mind the duet and octet rules. In this video, we'll use these steps to construct the Lewis diagram of formaldehyde (CH₂O). https://cdn.kastatic.org/ka-youtube-converted/s0VM7WKnPeA.mp4/s0VM7WKnPeA.mp4 368 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:molecular-and-ionic-compound-structure-and-properties/x2eef969c74e0d802:lewis-diagrams/v/exceptions-to-the-octet-rule 2022-09-07T08:21:01.673602243Z Exceptions to the octet rule While most atoms obey the duet and octet rules, there are some exceptions. For example, elements such as boron or beryllium often form compounds in which the central atom is surrounded by fewer than eight electrons (e.g., BF₃ or BeH₂). In contrast, many elements in the third-row and beyond have been observed to exceed the octet rule, forming compounds in which the central atom is surrounded by more than eight electrons (e.g. ICl₄⁻ or PF₅). Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/d12c78ae-4718-4fae-9cfe-d5fff448d594_1280_720_base.png Exceptions to the octet rule While most atoms obey the duet and octet rules, there are some exceptions. For example, elements such as boron or beryllium often form compounds in which the central atom is surrounded by fewer than eight electrons (e.g., BF₃ or BeH₂). In contrast, many elements in the third-row and beyond have been observed to exceed the octet rule, forming compounds in which the central atom is surrounded by more than eight electrons (e.g. ICl₄⁻ or PF₅). https://cdn.kastatic.org/ka-youtube-converted/Tkb1OemB2KI.mp4/Tkb1OemB2KI.mp4 430 Lewis structures of ionic and covalent compounds https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:molecular-and-ionic-compound-structure-and-properties/x2eef969c74e0d802:lewis-diagrams/e/lewis-diagrams 2026-03-27T03:10:09.572549356Z Lewis diagrams Check your understanding of Lewis diagrams in this set of free practice questions designed for AP Chemistry students. Lauren Rosebrugh exercise