Consider that the lithium atom has an inner shell of 2 electrons, just like helium.
Being only 1 electron away from the helium noble gas structure, lithium has a tendency
to lose its extra electron so it can be like helium as shown by the following:
Li Li + e-
(2.3.1)Note that the product of this reaction is no longer a neutral atom, but is a positively
charged Li+ cation. In losing an electron to become a cation, the lithium atom is said to
be oxidized. When lithium forms chemical compounds with other elements, it does so
by losing an electron from each lithium atom to become Li+ cations. These, then, are
attracted to negatively charged anions in ionic compounds.
Lithium compounds have some important uses. One of the most important lithium
compounds is lithium carbonate, Li 2 CO 3. It is widely prescribed as a pharmaceutical
to alleviate the symptoms of mania in manic-depressive and schizo-affective mental
disorders. Lithium carbonate is the most common starting material for the preparation
of other lithium compounds and is an ingredient of specialty glasses and enamels.
Lithium carbonate is also used in making special kinds of ceramic ware that expand only
minimally when heated. Lithium hydroxide, LiOH, is used to formulate some kinds of
lubricant greases and it is also used in some long-life alkaline storage batteries.
A particularly interesting application of lithium is its use in combination with
iodine to make cells used as sources of electricity for cardiac pacemakers. Implanted
in the patient’s chest, some of these pacemakers have lasted for 10 years before having
to be replaced.
2.5. The Second Period of the Periodic Table
The first period of the periodic table is a short one consisting of only two elements,
hydrogen and helium. Lithium, atomic number 3 begins the second period, which has 8
elements. Elements with atomic numbers 4-10, which complete this period, are discussed
in this section.
Beryllium, Atomic Number 4
Like atoms of all the elements in the second period of the periodic table, beryllium,
atomic number 4, atomic mass 9.012, has 2 inner shell electrons. Beryllium also has
2 outer shell electrons, so its Lewis symbol is
Be
In addition to 4 protons in their nuclei, beryllium atoms also have 5 neutrons. When the
beryllium atom is oxidized to form a beryllium cation, the reaction is
Be: → Be2+ + 2e- (lost to another atom) (2.5.1)36 Green Chemistry, 2nd ed