Formation of Positive Ions
|Metals usually have 1-4 electrons in the outer energy level. The electron arrangement of a rare gas is most easily achieved by losing the few electrons in the newly started energy level. The number of electrons lost must bring the electron number "down to" that of a prior rare gas.|
How will sodium complete its octet?
First examine the electron arrangement of the atom. The atomic number is eleven, therefore, there are eleven electrons and eleven protons on the neutral sodium atom. Write the Bohr diagram and Lewis symbol for sodium: (see Graphic on the right)
|This analysis shows that sodium has only one electron in its outer level. The nearest rare gas is neon with 8 electron in the outer energy level. Therefore, this electron is lost so that there are now eight electrons in the outer energy level, and the Bohr diagrams and Lewis symbols for sodium ion and neon are identical. The octet rule is satisfied.|
SUMMARY PRINCIPLE OF POSITIVE IONS
A positive ion is formed by the loss of negatively charged electrons. Although the number of protons does not change in the ion, there is an excess number of protons over electrons which produces the positive charge. All electrons in the outer energy level are lost.
Elemental atoms generally lose, gain, or share electrons with
in order to achieve the same electron structure as the nearest rare gas with eight
electrons in the outer level.