Changes

==Organization==

==Organization==

Elements in the periodic table are ordered by number of [[proton]]s, and rows are arranged by number of [[electrons]] in their outermost [[electron shell]].  Since farther out shells have more [[orbital]]s, this means that there will be more elements in the lower rows of the periodic table than in the higher rows.  For example, for [[principle quantum number] <i>n=1</i>, there is only one [[s-orbital]] available, which will fit only two electrons (due to the [[Pauli exclusion principle]], which states that no two electrons can have the same quantum numbers).  Therefore, only two elements can be in the top row of the periodic table.  As the [[principal quantum number]] increases, the number of electrons per shell rises, so the farther-down rows hold more elements.

Elements in the periodic table are ordered by number of [[proton]]s, and rows are arranged by number of [[electrons]] in their outermost [[electron shell]].  Since farther out shells have more [[orbital]]s, this means that there will be more elements in the lower rows of the periodic table than in the higher rows.  For example, for [[principal quantum number]] <i>n=1</i>, there is only one [[s-orbital]] available, which will fit only two electrons (due to the [[Pauli exclusion principle]], which states that no two electrons can have the same quantum numbers).  Therefore, only two elements can be in the top row of the periodic table.  As the principal quantum number increases, the number of electrons per shell rises, so the farther-down rows hold more elements.

The [[group number]] tells how many electrons an element has in its outermost electron shell.  For example, every element in group 8A, the [[noble gas]]es, has its outermost electron shell completely full.

The [[group number]] tells how many electrons an element has in its outermost electron shell.  For example, every element in group 8A, the [[noble gas]]es, has its outermost electron shell completely full.