http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Atoms are composed of a central nucleus, containing positively-charged protons and neutrally-charged neutrons. Smaller, negatively-charged electrons travel around the nucleus in layered orbits called shells.
Title from resource description page (viewed September 12, 2022).