Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: Want to explore more? Check out the full middle school playlist here: 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. 00:00 Intro 00:40 What are atoms? 02:45 How small are atoms? 03:34 Summary Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic…
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