PS-4.1   Explain the role of bonding in achieving chemical stability.
Key Concepts:
Stability:  bond, noble gas configuration, helium structure
Nonmetals, Metals
  The Noble gases listed in group 18 of the periodic table are chemically stable. Chemical Stability, for an atom, is achieved by having an outer energy level filled with electrons. For the element Helium this stability is achieved with 2 electrons filling the highest or outer energy level. You will recall that the highest energy level is called the valence level. For most other Noble gases, 8 valence electrons ( a stable octet) fill the outer energy level. A noble gas electron configuration is chemically stable, and all atoms would be more stable if they had this electron configuration. When atoms bond chemically they do so by either sharing or transferring valence electrons to achieve a stable valence electron structure like the nearest Noble gas.
Diagram L
         The  metals, especially those in groups 1 and 2, tend to transfer electrons to Group 16 or Group 17 nonmetals when possible. This happens because metals generally have 3 or fewer valence electrons. These electrons represent low energy when compared to the nonmetals in groups 16 and 17 that have 6 or 7 valence electrons.
          Diagram "L" above shows the first two periods of the periodic table. A Lithium atom, shown here as the first atom in period 2, can give up its single valence electron to a nonmetal, like Fluorine, in order to achieve the stable electron structure of Helium.
Diagram M
    In diagram "M" a Lithium atom gives up its 1 valence electron to a Fluorine atom. Both the lithium and the Fluorine achieve a stable electron structure.  The Lithium atom now has 2 valence electrons like Helium and the Fluorine atom new has 8 valence electrons like Neon. In the process the Lithium atom picks up a charge of 1+ and the Fluorine atom picks up a charge of 1-
Metals lose electrons to achieve a stable noble gas structure and nonmetals gain electrons to achieve a noble gas structure.  When metals lose electrons and nonmetals gain electrons, they bond and become stable through ionic bonding. ( It's called ionic bonding because the oppositely charged ions attract each other.)
Nonmetals bond with each other by sharing electrons to become stable through covalent bonding.