This document lists several chemical elements in their native symbols along with some notes. It provides the symbols of common elements like hydrogen, helium, aluminum, carbon, calcium, oxygen, nitrogen, neon, chlorine, phosphorus, curium, and roentgenium. It notes that the elements have their own unique atomic structures. Some elements like hydrogen, carbon, nitrogen, and phosphorus have their atomic mass precisely defined. Some elements like helium, calcium, aluminum, and neon have both their atomic mass and structure precisely defined.