2. How Electrons are Configured in Energy Shells

3.   The lowest energy arrangement of electrons is the most stable. When electrons are arranged in the lowest possible energy arrangement it is called the electron’s ground-state electron configuration. Electron’s Lowest State

4.   Three rules (principles) define how electrons are arranged in orbit around an atom’s nucleus.  First Rule:  Aufbau’s principal states that each electron occupies the lowest energy orbital available. Rules for Placing Electrons in Energy Shells

5.   Pauli’s exclusion principal states that a maximum of two electrons may occupy a single atomic orbital but only if they spin in opposite directions.  Hund’s Rule states that single electrons with the same spin must each occupy an equal-energy orbital before additional electrons with different spins can occupy the same orbitals. 2 nd & 3 rd Rule

6.   There are seven principal energy levels (shells).  Each principal energy level contains sublevels.  Each sublevel contains orbitals. The orbitals are where the electrons reside.  Each orbital allows only two electrons. Energy Levels & Sublevels

7.   The sublevels are designated s, p, d and f.  The s sublevels are spherical, contain one orbital, and can hold a total of two electrons.  The p sublevels resemble dumbbells. There are three p orbitals each allowing two electrons. The total number of electrons able to occupy the p sublevels is six. s & p Sublevels

8.   The shapes of the d and the f sublevels become more complicated. The d sublevels have five orbitals and can hold a maximum of 10 electrons while f sublevels contains 7 orbitals and can hold a maximum of 14 electrons.  The superscripts inform us how many electrons are residing in an orbital. d & f Sublevels