Thallium: Metallic Chemical Elements

Metallic chemical element chemically active, soft white color, symbol Cs, is located in the first group of the periodic table which means that he belongs to a group of alkaline elements. Atomic number 55 and atomic weight 132.905, the melting point of 28.4 degrees Celsius and a boiling point of 671 degrees Celsius and density of 1.87 g / cm 3. Cesium was discovered in 1860 by the German chemist Robert Bunsen, German physicist Gustav Kirchoff during the use of the spectroscope when they analyzed the spectrum of mineral water. Characterized by the metal in the spectrum containing two bright lines in the blue along with several others in red, yellow, and green. Because of its ability to release electrons when exposed to light, it enters into

Cesium and plays a role in the nuclear generators hydrodynamic.

Atomic Clock.

Lide, David R., ed. CRC handbook of chemistry and physics. Vol. 85. CRC press, 2004.p 4-8

Thallium

Thallium is a soft metal with a gray color bluish, like lead and are getting most of the thallium from iron pyrites, where there are traces of this element as one of the impurities in it. Also it included in some metals such as crooksite, and lorandite. English scientist Sir William Crookes discovered thallium in 1861.

Atomic number for thallium 81g, atomic weight 204.383g . him The melting temperature of 303.5 °C, while boils at a temperature of 1457 ° C. And its density is 11.85 g / cm² at 20 ° C class

The metal thallium is highly toxic to humans. As the feature is a cumulative effect, it increases with the passage of time. And exposure to a lot of this element may cause some diseases and suspected thallium potential carcinogenic to humans. Thallium and its compounds have many uses, but these uses are limited because of its chemical nature is very toxic. The compound is used in photovoltaic cells and as an insecticide and household rodents.Thallium sulfate is also used in abundance poison for ants and

CRC handbook of chemistry and physics. Vol. 85. CRC press, 2004,p4-18

Zinc

Zinc, an element with an atomic weight of 65, is classified as a Group IIB post-transition member of the periodic table. The Group IIB metals below zinc in the periodic table are cadmium and mercury ,Zinc is generally considered a relatively nontoxic metal . This classification is based on several characteristics: 1) zinc is a metal essential to hundreds of biological processes 2) zinc is relatively abundant in the natural environment;

3) the recommended daily allowance(RDA) of zinc in the human population is 8 to 15 mg higher than many other essential metals, 4) zinc does not appear to accumulate in the body with age , 5) there are no known genetic abnormalities which result in excessive accumulation of zinc in the body, unlike metals such as copper (Wilson's disease) and iron (hemochromatosis).

The US Environmental Protection Agency standard for maximum zinc concentration drinking water is 5