https://www.khanacademy.org/science/ms-chemistry/xc370bc422b7f75fc:classifying-matter/xc370bc422b7f75fc:elements-and-atoms/v/elements 2025-01-16T17:32:17.772857468Z Elements Elements are the fundamental building blocks of all matter, just as letters form the basis of all writing. With only about 100 natural elements, nature constructs everything around us—from tiny microbes to vast oceans and stars. These elements, represented by symbols on the periodic table, combine in countless ways to create the diverse materials that make up the universe. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/7bad28ff-1c16-4904-860d-48ebd21ceb41_1280_720_base.png Elements Elements are the fundamental building blocks of all matter, just as letters form the basis of all writing. With only about 100 natural elements, nature constructs everything around us—from tiny microbes to vast oceans and stars. These elements, represented by symbols on the periodic table, combine in countless ways to create the diverse materials that make up the universe. https://cdn.kastatic.org/ka-youtube-converted/PeNjuIQFd9U.mp4/PeNjuIQFd9U.mp4 313 Atoms and molecules https://www.khanacademy.org/science/ms-chemistry/xc370bc422b7f75fc:classifying-matter/xc370bc422b7f75fc:elements-and-atoms/v/atoms 2025-01-16T17:32:17.772857468Z Atoms An atom is the smallest particle of an element that still retains all the properties of that element. Early philosophers imagined atoms as indivisible units that make up all matter, an idea revived and developed by scientists like John Dalton. Atoms are incredibly small and numerous—a single gold ring contains more atoms than stars in the universe, highlighting their fundamental role in forming the matter we see. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/6f8dc03b-b8ae-49fe-b3c7-28487059ceae_1280_720_base.png Atoms An atom is the smallest particle of an element that still retains all the properties of that element. Early philosophers imagined atoms as indivisible units that make up all matter, an idea revived and developed by scientists like John Dalton. Atoms are incredibly small and numerous—a single gold ring contains more atoms than stars in the universe, highlighting their fundamental role in forming the matter we see. https://cdn.kastatic.org/ka-youtube-converted/KyBgxe-rU48.mp4/KyBgxe-rU48.mp4 248 Atoms and molecules https://www.khanacademy.org/science/class-9-chemistry/x46dd29ce84a663ea:atoms-and-molecules/x46dd29ce84a663ea:what-is-an-atom/e/understand-elements-and-atoms 2025-12-18T17:50:52.903549868Z Understand: elements and atoms Check your understanding of elements and atoms in this set of free, standards-aligned practice questions. Allen Ruch exercise https://www.khanacademy.org/science/ms-chemistry/xc370bc422b7f75fc:classifying-matter/xc370bc422b7f75fc:compounds/v/compounds-and-chemical-formulas 2025-01-16T17:32:17.772857468Z Compounds and chemical formulas Some substances, like copper or gold, are pure elements. Others, like water (H₂O), are compounds—made from two or more elements in fixed ratios, chemically bonded. Each compound has a unique formula, like CO₂ for carbon dioxide, representing its specific atomic arrangement. Compounds form molecules, tightly bonded units, creating an incredible diversity of substances in nature. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/e3e4181e-5236-462c-82b7-64099d59b95c_1280_720_base.png Compounds and chemical formulas Some substances, like copper or gold, are pure elements. Others, like water (H₂O), are compounds—made from two or more elements in fixed ratios, chemically bonded. Each compound has a unique formula, like CO₂ for carbon dioxide, representing its specific atomic arrangement. Compounds form molecules, tightly bonded units, creating an incredible diversity of substances in nature. https://cdn.kastatic.org/ka-youtube-converted/36nlbUdRvUM.mp4/36nlbUdRvUM.mp4 361 Atoms and molecules https://www.khanacademy.org/science/ms-chemistry/xc370bc422b7f75fc:classifying-matter/xc370bc422b7f75fc:compounds/e/understand-compounds-and-chemical-formulas 2026-03-11T01:40:33.014543209Z Understand: compounds and chemical formulas Check your understanding of compounds and chemical formulas in this set of free, standards-aligned practice questions. Allen Ruch exercise