Atomic structure worksheet with handwritten annotations showing calculations for protons, neutrons, and electrons for Carbon-12.

A worksheet titled "Atomic Structure" with a table listing isotopes, atomic numbers, mass numbers, and calculations for protons, neutrons, and electrons. Handwritten notes and arrows highlight the mass number and atomic number for Carbon-12 (C-12), showing calculations like 12-6=6 for neutrons. The table includes other isotopes such as Mo-96, Fe-56, and Cu-65.