Atomic Physics Physics 100 Chapt 24 Dimitri Mendeleev

Periodic table of elements Elements in vertical rows have similar chemical properties Inert gasses

Schroedinger’s Equation for multi- electron Atoms

Allowed energy levels are clustered in “shells” n # of states a 8 3b 10 4a 8 4b 10 4c 14

Pauli exclusion principle Only one electron per quantum state Once a quantum state is occupied additional electrons are excluded Wolfgang Pauli

Light elements Hydrogen Helium Lithium Neon 1 electron in outermost shell outermost shell is full

Periodic table of elements Elements in vertical rows have similar chemical properties 1 e - in outer shell Filled outer shell

Chemical properties depend upon the outermost shell configuration Oxygen Sulfur Outermost shells Have 2 vacancies

Periodic table of elements 2 vacancies in outer shell

Atoms combine to form molecules by filling outer shells Oxygen +1 - Hydrogen +1 - Hydrogen Water=H 2 O

Atoms combine to form molecules by filling outer shells Carbon +1 - Hydrogen +1 - Hydrogen Methane=CH Hydrogen +1 - Hydrogen

Elements with full outer shells don’t form molecules Helium Neon Argon Noble gasses

Periodic table revisited Elements in vertical rows have same outer shell configurations Outer shell is full 1 elec in outer shell 2 vacancies in outer shell 4 e - in outer shell