Electron Arrangement
 Electrons can be found around the nucleus in threedimensional energy levels.
 Electrons can not be found in between energy levels.
 They can move from one energy level to the next.
 The electron’s energy ____________ as it moves to
higher energy levels.
 When the electron moves to a lower energy level it
releases energy in the form of _________ (photon).
 An element’s period number is the same as the number
of energy levels that it’s electrons occupy
 Expressed as: Bohr-Rutherford Diagrams
Lewis Structures
Ionization – when an atom gains an electron an ________
is formed: Cl + e-  Cl1-. There are more electrons than
protons.
When an atom loses an electron a _________ is formed:
Na  Na1+ + 1e-. There are fewer electrons than protons.
Noble Gases
 Group VIII elements are the only elements that exist
as individual atoms in nature.
 Extremely unreactive because outer energy level is full.
 Noble gases have a ____________ octet.