Elements and atoms | Atoms, compounds, and ions | Chemistry | Khan Academy
Why the open web links it
Explains the basics of elements and atoms, including protons, neutrons, and electrons.
Linked by 7 independent sites, 3 of them widely read in the 2026-10 crawl of the open web, including unh.edu, maricopa.edu, lumenlearning.com, 2cool4school.org, josefstepanek.cz.