The last six elements in period four are Gallium (Ga - 31), Germanium (Ge - 32), Arsenic (As - 33), Selenium (Se - 34), Bromine (Br - 35) and Krypton (Kr - 36). These elements are created when the 4p orbital is filled.
Gallium is in the same group as Aluminum but it melts at 850F so is very soft at room temperature. It also is one of only a few substances, the most notable being water, that are more dense in a liquid state than as a solid.
Germanium is in Group 14 with Carbon and Silicon. It is considered a metalloid and is most frequently used in optical systems due to its high index of refraction.
Arsenic forms many toxic substances, most notably Arsenic Trioxide, which inhibits ATP production.
Selenium is a semiconductor with the unusual property of conducting electricity better in the light than in the dark, and is used in photocells. It is also a popular trace element in vitamin and mineral supplements, functioning as a cofactor for the reduction of antioxidant enzymes and plays a role in the functioning of the thyroid gland.
Bromine is in the same group as Chlorine, the halogens. It is a dark, reddish brown liquid at room temperature, covered by a layer of gaseous Bromine which is dark orange. It exists as Br2. Bromine's primary use is in organobromine compounds as a flame retardant.
Krypton is a Noble gas. It does not stop Superman, that is Kryptonite an as yet undiscovered element with an atomic number of 126. Like the other noble gases, Krypton can be used in lighting and photography as it has a high number of spectral lines and a high light output.
This completes the first four periods of the Periodic Table and most of the biologically active elements. Next we will look at some specific individual elements of Period Five and up as well as several groups consisting of elements in periods four, five and six, including the precious metals.
No comments:
Post a Comment