Download Group 4A Elements DOC

Kenneth Waterson
Rachelle Burch
Christine Bodden
Cassy Peterson
Group 14 Elements (The Tetrels)
The group 14 elements are also known as the tetrel elements. They can arguably
be called the most important of all elements. Carbon, which is the first of the group,
provides the basis of life on earth and silicon, which is also in the group, is vital for the
physical structure of the natural environment. This group is also a very diverse group in
its physical properties and is made up of non-metals, metalloids, and metals. Carbon and
Silicon are the non-metals, while Germanium is the metalloid, and Tin and Lead are the
metals. All of these compounds are solid at room temperature and they like to form
tetrahedral compounds but also have the ability to form double bonds. The dominant
oxidation state of group 14 is +4 in the compounds of these elements. The major
exception to this is lead, whose most common oxidation state is +2 because of the inert
pair effect with 2 p electrons being lost.
The increase in metallic properties, as mentioned above, as you go down the
family, can be understood in terms of the increasing ionic radius and associated decrease
in ionization energy down the group. This is because ionization energies of heavier
elements are low, so the metals form cations more readily down the group. Also if you
get rid of carbon (first row anomaly), the bond energies in both X-X and X-H bonds
decrease as you go down the group. Furthermore, the electron affinity decreases down
the group, but the electro negativity varies down the group.
Carbon is considered to be a part of the first row anomaly that sets all second
period elements apart from others in their families. It is arguably the most important
element on the entire periodic table—so important that all other atomic masses are
calibrated against carbon-12. But, it is not important just for this reason; carbon is the
most diverse element on the planet in that it can form bonds with itself, its non-metal and
metalloid “neighbors” on the periodic table, halogens, alkali metals, alkaline Earth metals
and a host of transition metals. Its compounds can be either organic or inorganic in
nature. The most complex of its structures are organic. Due to its ability to form up to
four sigma (σ) bonds, carbon can be found in chains, branches and rings with elements
like hydrogen, nitrogen, oxygen and sulfur. This leads to a multitude of compounds with
a wide variety of physical properties. Conversely, inorganic metal carbonates tend to be
in a main mineral form. These would be compounds such as limestone, chalk, marble
and coral.
In nature, carbon exists in its pure form as graphite, coal and diamond. All three
require different heats of formation and take different amounts of time. Diamonds
require the highest heat of formation. Carbon forms two of the most important gaseous
oxides needed to sustain life, these being carbon monoxide and carbon dioxide.
The industrial and biological contributions of carbon are plentiful. Because of its
unique ability to form long C-C chains or rings, carbon is able to form an enormous range
of organic compounds. Diamonds, one of the hardest and most beautiful substances on
earth, are covalently bonded in a rigid structure. Their personal uses are obvious, but
diamonds are also widely employed industrially, often to cut through other hard
substances. Carbon, especially in its 2-dimensional lattice form, rubs off itself easily (as
in graphite, present in pencils), making it exceptional as an industrial lubricant. Carbon
in its graphite form can also refract light, allowing it to withstand high temperatures. For
this reason, graphite compounds are present in particularly warm spaces, such as the
inside of ovens.
Carbon containing compounds are present in a large variety of industrial
applications, including black paint, explosives, certain cathrode ray tubes, rubber tires,
typewriter ribbons, phonograph records, carbonated beverages and fuels (hydrocarbons).
The biological applications of carbon are as diverse as those of industry. First and
foremost, carbon is essential to organic life; nearly every molecule in a living organism
contains it. Carbon dioxide is essential in the gaseous exchange needed to sustain aerobic
creatures and plant life. Carbon can also be found in the vast majority of pharmaceuticals
today, as they are organic substances which must be easily received by the organic
human body.
The other elements of the tetrel group are also widely used in industry. Silica is
used to make glass. Germanium was widely used for the construction of transistors. Tin is
resistant to corrosion and is therefore used to plate steel in tin cans. Tin is also used along
with lead in solder alloys. Window glass is made by floating molten glass on the surface
of molten tin. Tin compounds are also used as fungicides and biocides.
Lead, with an atomic number 82, is the last of the tetrel group. While many
different industrial uses for lead exist, by far the biggest use of lead worldwide is for the
lead-acid battery. Lead-acid batteries contain grids made of lead-antimony alloy and
minor additions of elements such as copper, arsenic, tin (another tetrel group member),
and selenium. The spaces in the grids are filled with a lead oxide based paste. When the
plates are immersed in sulfuric acid they form an electric cell that produces electricity.
The basic chemical reactions that occur to produce this electricity require the presence of
lead dioxide and lead metal. Each cell produces a voltage of 2V. Lead is chosen for this
type of battery because it is highly conductive and resistant to corrosion. The different
types of lead-acid batteries are SLI, traction, and stationary. These batteries power cars,
airport support vehicles, and stand-by emergency power sources. “Giant” lead-acid
batteries have even caught the eye of large industrial users of electricity.
References
Atkins, P.; Overton, T.; Rourke, J.; Weller, M.; Armstrong, F. Inorganic Chemistry; 4th
Edition; W. H. Freeman and Company: New York, NY, 2006.
Chemical Elements; Carbon, Thomson Learning, Inc.: Lawrenceville, NJ, 2005-2006.
Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change; 3rd
Edition; McGraw Hill Publishing Inc: New York, NY, 2003.
Lead Products and Their Uses; Lead-acid batteries. Lead Development Association
International: London; http://www.ldaint.org/technotes4.htm. Accessed 9April 2007.