How can elements achieve a stable electron configurations?

Aug 20, 2014

A stable electron configuration for the representative or main group elements is a noble gas configuration. The main group or representative elements are in Groups 1, 2, 13-18 (IA, IIA, IIIA - VIIIA) on the periodic table. The noble gases are in Group 18 (VIIIA). Atoms of the representative elements achieve a noble gas configuration by gaining or losing electrons and becoming ions, or by sharing electrons.

Helium (He), in Period 1, is the first noble gas and has an electron configuration of ${\text{1s}}^{2}$. The atoms of the element hydrogen (H) (${\text{1s}}^{1}$) typically share one electron with another hydrogen atom, or an atom of another element, in order to achieve the noble gas configuration of helium.

In Period 2, lithium atoms (${\text{1s"^2"2s}}^{1}$) in Group 1 lose their single valence electron to become a positively charged 1+ ion, and beryllium atoms ($\text{1s"^2"2s"^2}$) in Group 2 will lose their two valence electrons to become 2+ ions. After losing their valence electrons, lithium and beryllium ions will have the noble gas configuration of helium in Period 1. The atoms of the rest of the representative elements (Groups 13-17) in Period 2 will gain, lose, or share electrons in order to achieve the noble gas of Neon ($\text{1s"^2"2s"^2"2p"^6}$) at the end of Period 2.

The rest of the representative elements (Groups 1, 2, 13-17), will follow the same pattern as the Period 3 elements. The atoms of the Group 1 and 2 elements will lose their valence electrons in order to achieve the electron configuration of the noble gas in the previous period, and the atoms of the Groups 13-17 elements will lose, gain, or share electrons in order to achieve the electron configuration of the noble gas at the end of that period.

The transition elements (Groups 3-13) behave differently, and many form ions of more than one charge, such as iron (Fe), which can form 2+ and 3+ ions. But they still lose electrons to form positively charged ions with stable electron configurations, but not noble gas configurations.