Crapter Atomic Structure and Bonding §1.1 Atomic structure Atomic numbers and atomic masses 1. Atomic models M-shell 1 Electron L-Shell 2 Electrons K-Shell 2 Electrons Nucleus 11 Protons 12 Neutrons§1.1 Atomic structure ◆ Ⅰ.Atomic numbers and atomic masses 1. Atomic Models Chapter I Atomic Structure and Bonding