https://www.khanacademy.org/science/chemistry/atomic-structure-and-properties/copy-of-periodic-table-of-elements/v/periodic-table-groups 2022-09-07T08:21:01.673602243Z Groups of the periodic table The s-, p-, and d-block elements of the periodic table are arranged into 18 numbered columns, or groups. The elements in each group have the same number of valence electrons. As a result, elements in the same group often display similar properties and reactivity. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/bf6fd19a-167e-41d3-a67f-7032ecf1249b_1280_720_base.png Groups of the periodic table The s-, p-, and d-block elements of the periodic table are arranged into 18 numbered columns, or groups. The elements in each group have the same number of valence electrons. As a result, elements in the same group often display similar properties and reactivity. https://cdn.kastatic.org/ka-youtube-converted/jQGUkJc7_04.mp4/jQGUkJc7_04.mp4 461 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/chemistry/atomic-structure-and-properties/copy-of-periodic-table-of-elements/v/periodic-table-valence-electrons 2021-01-04T18:35:18Z Counting valence electrons for main group elements How to determine the number of valence electrons and draw Lewis structures for main group elements starting from the electron configuration. Jay video https://cdn.kastatic.org/googleusercontent/UM_zq-AgN6BvQffC5MkOKPZUR_g7MBHJ_Rjzahf-X-lloYy6zpUrDKpZt9dW02VYOnBLa572QwLS_dsl20u2vms Counting valence electrons for main group elements How to determine the number of valence electrons and draw Lewis structures for main group elements starting from the electron configuration. https://cdn.kastatic.org/ka-youtube-converted/akm5H2JsccI.mp4/akm5H2JsccI.mp4 499 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:atomic-structure-and-properties/x2eef969c74e0d802:periodic-trends/v/group-trend-for-ionization-energy 2020-08-28T01:50:07Z Ionization energy: group trend An element's first ionization energy is the energy required to remove the outermost, or least bound, electron from a neutral atom of the element. On the periodic table, first ionization energy generally decreases as you move down a group. This is because the outermost electron is, on average, farther from the nucleus, meaning it is held less tightly and requires less energy to remove. Jay video https://cdn.kastatic.org/googleusercontent/2LyY-rZJgaHqGfQ2logedUkcFo-cinTMJQXeddxMk3glTPzlOWhoYuxds0LU_0W14kE2sbFCY_rW-td5nfJo25TU Ionization energy: group trend An element's first ionization energy is the energy required to remove the outermost, or least bound, electron from a neutral atom of the element. On the periodic table, first ionization energy generally decreases as you move down a group. This is because the outermost electron is, on average, farther from the nucleus, meaning it is held less tightly and requires less energy to remove. https://cdn.kastatic.org/ka-youtube-converted/vQLcxlvK7Ik.mp4/vQLcxlvK7Ik.mp4 619 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-9-chemistry-snc-aligned/x22d5b83c2ea2dc38:periodic-table-and-periodicity/x22d5b83c2ea2dc38:features-of-modern-periodic-table/v/electron-configurations-with-the-periodic-table-pk 2025-12-18T16:50:45.096818701Z Electron configurations with the periodic table Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Electron configurations with the periodic table Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/KTnr6WeGqwY.mp4/KTnr6WeGqwY.mp4 879 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:atomic-models-and-periodicity/x2613d8165d88df5e:the-quantum-model/v/introduction-to-electron-configurations 2021-05-26T15:51:55Z Introduction to electron configurations Electron configurations describe where electrons are located around the nucleus of an atom. For example, the electron configuration of lithium, 1s²2s¹, tells us that lithium has two electrons in the 1s subshell and one electron in the 2s subshell. Sal Khan video https://cdn.kastatic.org/googleusercontent/7qvxjh_LjGjrWRL3b-2aGr7nmfGbMjeckykwlEfIvMJz9LPmUOTJSsWxrNI-fc58qAHMD2gEoo0Br36E3idGo3vk Introduction to electron configurations Electron configurations describe where electrons are located around the nucleus of an atom. For example, the electron configuration of lithium, 1s²2s¹, tells us that lithium has two electrons in the 1s subshell and one electron in the 2s subshell. https://cdn.kastatic.org/ka-youtube-converted/LyFzELsUgBU.mp4/LyFzELsUgBU.mp4 308 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:alkaline-earth-metals/x7a43e770fc9e15cf:electronic-structure-trends-and-reactivity-of-group-2-elements/v/metals-reacting-with-water-pk 2025-12-18T18:40:53.641757593Z Metals reacting with water Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Metals reacting with water Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/MlSmof_sPzY.mp4/MlSmof_sPzY.mp4 646 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:electrochemistry/x7a43e770fc9e15cf:activity-series-prediction-of-redox-feasibility/v/metals-reacting-with-oxygen-pk 2025-12-18T18:40:53.641757593Z Metals reacting with oxygen Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Metals reacting with oxygen Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/5WvnPf-MOOw.mp4/5WvnPf-MOOw.mp4 388 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-9-chemistry-snc-aligned/x22d5b83c2ea2dc38:acid-base-chemistry/x22d5b83c2ea2dc38:reactions-of-acids-and-bases/v/metals-reacting-with-acid-pk 2025-12-18T16:50:45.096818701Z Metals reacting with acid Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Metals reacting with acid Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/LmE6b0eXUOk.mp4/LmE6b0eXUOk.mp4 376 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:electrochemistry/x7a43e770fc9e15cf:activity-series-prediction-of-redox-feasibility/v/reactivity-series-pk 2025-12-18T18:40:53.641757593Z Reactivity series Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Reactivity series Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/Hle5xoeuIgM.mp4/Hle5xoeuIgM.mp4 416 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:alkaline-earth-metals/x7a43e770fc9e15cf:electronic-structure-trends-and-reactivity-of-group-2-elements/v/metal-and-non-metal-oxides-reacting-with-acids-and-bases-pk 2025-12-18T18:40:53.641757593Z Metal and non metal oxides, reacting with acids and bases Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Metal and non metal oxides, reacting with acids and bases Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/X8qqwbTGIGk.mp4/X8qqwbTGIGk.mp4 460 Electronic structure, trends, and reactivity of group 2 elements https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:atomic-models-and-periodicity/x2613d8165d88df5e:the-periodic-table/a/determine-valence-electrons-using-the-periodic-table 2025-03-12T16:31:14.708488543Z Determine valence electrons using the periodic table Learn how to determine the number of valence electrons for an element using the periodic table. article https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:atomic-models-and-periodicity/x2613d8165d88df5e:the-quantum-model/a/the-periodic-table-electron-shells-and-orbitals-article 2024-02-03T14:54:13.458936091Z The periodic table, electron shells, and orbitals article https://www.khanacademy.org/science/revision-term-1-tg-chemistry-class-11/x3f2cd496ba25689a:week-1/x3f2cd496ba25689a:classification-of-elements-and-periodicity-in-properties/e/electron-configurations-exercise 2022-12-29T09:00:16.314334179Z Electron configurations Practice writing electron configurations Yuki exercise https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:alkaline-earth-metals/x7a43e770fc9e15cf:electronic-structure-trends-and-reactivity-of-group-2-elements/e/electronic-configurations-practice 2026-01-03T08:04:42.460383575Z Electronic configurations (part 2) Let's solve a few more questions based on how electronic configuration positions different elements in the periodic table. Revathi exercise https://www.khanacademy.org/science/grade-12-chemistry-snc-aligned/x7a43e770fc9e15cf:alkaline-earth-metals/x7a43e770fc9e15cf:electronic-structure-trends-and-reactivity-of-group-2-elements/e/trends-in-physical-properties-of-alkaline-earth-metals 2023-01-09T11:18:41.843090067Z Chemical properties of alkaline earth metals and their compounds Let's understand the various trends in the atomic and physical properties of group-2 elements by solving these questions. Revathi exercise https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:atomic-models-and-periodicity/x2613d8165d88df5e:the-periodic-table/e/apply-number-of-valence-electrons 2024-06-26T17:43:47.400140177Z Apply: number of valence electrons Apply your knowledge of valence electrons for main group elements in this set of free practice questions. Emily Cizmas exercise https://www.khanacademy.org/science/odia-class-10-physical-sciences/x28e877d8a7566183:metals-and-non-metals/x28e877d8a7566183:reactivity-series/e/reactivity-of-metals-overview 2026-04-07T23:17:37.123726494Z Reactivity of metals (overview) Let's check our understanding of reactivity series of metals by solving some application-based questions. exercise