https://www.khanacademy.org/science/bridge-course-class-11th-chemistry/x426c9d2c554669cb:basic-concepts-of-chemistry/x426c9d2c554669cb:laws-of-chemical-combination/e/laws-of-chemical-combination 2026-04-07T09:22:30.618598699Z Laws of chemical combination (basic) Let's solve a few problems to understand the laws of chemical combination. Aanchal Arora exercise https://www.khanacademy.org/science/ap-biology/chemistry-of-life/elements-of-life/v/elements-and-atoms 2023-03-31T23:16:47.953017837Z Elements and atoms Elements are pure substances with specific properties. Atoms are the smallest units of elements that still retain the element's properties. Atoms contain electrons, neutrons, and protons. Each element is defined by the number of protons in its nucleus. Sal Khan video https://cdn.kastatic.org/googleusercontent/zfLHeNHjPfEhSYfKtZLu6Ft_uFg2p_L9gALjUyfahbjdBzZbrDLxrg-rk_mrsUBBVIKs44ALBBI1Gv8cm2O_Ppa05g Elements and atoms Elements are pure substances with specific properties. Atoms are the smallest units of elements that still retain the element's properties. Atoms contain electrons, neutrons, and protons. Each element is defined by the number of protons in its nucleus. https://cdn.kastatic.org/ka-youtube-converted/IFKnq9QM6_A.mp4/IFKnq9QM6_A.mp4 789 Atoms and Molecules https://www.khanacademy.org/science/bridge-course-class-11th-chemistry/x426c9d2c554669cb:basic-concepts-of-chemistry/x426c9d2c554669cb:ionic-compounds/v/worked-example-formula-for-an-ionic-compound 2023-06-26T12:36:08.867767149Z Worked example: Formula for an ionic compound Let's understand how to write the formula for ionic compounds! Vibhor Pandey video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Worked example: Formula for an ionic compound Let's understand how to write the formula for ionic compounds! https://cdn.kastatic.org/ka-youtube-converted/rjsx6MP0Vos.mp4/rjsx6MP0Vos.mp4 211 Atoms and Molecules https://www.khanacademy.org/science/bridge-course-class-11th-chemistry/x426c9d2c554669cb:basic-concepts-of-chemistry/x426c9d2c554669cb:ionic-compounds/e/find-the-formula-for-ionic-compounds 2025-02-06T18:17:42.147590351Z Find the formula for ionic compounds Practice finding the formula when given the name of an ionic compound. Yuki exercise https://www.khanacademy.org/science/strengthened-shs-chemistry-1/x174677b2bfa4bea2:measurements-in-chemistry/x174677b2bfa4bea2:naming-compounds/v/naming-ionic-compounds-with-polyvalent-ions 2025-05-29T08:44:44.739717086Z Naming ionic compounds with polyvalent ions Let's understand naming of ionic compounds that contain polyvalent ions, using the example of cobalt (III) sulfide. Dubverse video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Naming ionic compounds with polyvalent ions Let's understand naming of ionic compounds that contain polyvalent ions, using the example of cobalt (III) sulfide. https://cdn.kastatic.org/ka-youtube-converted/GgxjXsf02rQ.mp4/GgxjXsf02rQ.mp4 242 Atoms and Molecules https://www.khanacademy.org/science/bridge-course-class-11th-chemistry/x426c9d2c554669cb:basic-concepts-of-chemistry/x426c9d2c554669cb:ionic-compounds/e/predict-charges-on-monatomic-ions 2025-04-09T10:12:02.040424533Z Predict the charge on monatomic ions Predict the monatomic ion formed from different elements based on the position in the periodic table. Yuki exercise https://www.khanacademy.org/science/class-9-chemistry/x46dd29ce84a663ea:atoms-and-molecules/x46dd29ce84a663ea:writing-chemical-formulae/e/predicting-the-formula-of-the-given-ionic-compound 2026-03-06T09:40:40.837655949Z Predicting the formula of the given compound Let's solve a few problems to identify the correct formula of a given ionic compound. Aanchal Arora exercise https://www.khanacademy.org/science/bmc-grade-9-science/x345505a97fc4a662:measurement-of-matter/x345505a97fc4a662:mole-concept/v/the-mole-and-avogadros-number 2025-05-29T08:44:44.739717086Z The mole and Avogadro's number One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions). The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant. Let's learn more about concept of the mole and how it can be used to convert between mass and number of particles. Dubverse video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw The mole and Avogadro's number One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions). The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant. Let's learn more about concept of the mole and how it can be used to convert between mass and number of particles. https://cdn.kastatic.org/ka-youtube-converted/MP1K0LNKQ7Q.mp4/MP1K0LNKQ7Q.mp4 536 Atoms and Molecules https://www.khanacademy.org/science/grade-9-chemistry-snc-aligned/x22d5b83c2ea2dc38:stoichiometry/x22d5b83c2ea2dc38:the-mole-and-molar-mass/e/converting-moles-and-mass 2026-04-07T09:22:30.618598699Z Converting moles and mass Practice converting moles to grams, and from grams to moles when given the molecular weight. Yuki exercise