Electronic Configurations ·Aufbau Principle: Place electrons in Relative orbital energies lowest energy 12p.↑2p,-2p. orbital first. ·Hund's Rule: energy ￥2s Equal energy orbitals are half- filled,then filled. Copyright2005 Pearson Prentice Hall,Inc. ·6C:1s22s22p2 二> Chapter 1 Chapter 1 7 Electronic Configurations • Aufbau Principle: Place electrons in lowest energy orbital first. • Hund’s Rule: Equal energy orbitals are half￾filled, then filled. • 6C: 1s 2 2s 2 2p 2    => 