Periodic Table of Atomic Numbers orbitals and shells Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers electron shell model Periodic Table of Atomic Numbers orbitals and shells Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Source Periodic Table of Atomic Numbers Periodic Table of Atomic Numbers Source