Discovery of silicon

Silica (SiO2) in the form of sharp flints were among the first tools made by humans. The ancient civilizations used other forms of silica such as rock crystal, and knew how to turn sand into glass. The manufacture of glass containing silica was carried out both by the Egyptians—at least as early as 1500 BCE—and by the Phoenicians. In 1789, the French chemist Antoine Lavoisier proposed that a new chemical element could be found in quartz. He was right about the new element. Silicon accounts for 28% of the weight of Earth’s crust.

In 1808 in England, Humphry Davy isolated partly pure silicon for the first time, but he did not realize it. He was mistaken that the new chemical element as a compound rather than an element.

In 1811, Joseph Gay Lussac and Louis Jacques Thénard reacted silicon tetrachloride with potassium metal and produced some very impure form of silicon. They did not, however, attempt to purify this new substance.

In 1824, Swedish chemist Jacob Berzelius produced a sample of amorphous silicon, a brown solid, by reacting potassium fluorosilicate with potassium and purifying the product by stirring it with water, with which it reacts, and thereby obtained relatively pure silicon powder. He named the new element silicium. Today, silicon is produced by heating sand (SiO2) with carbon to temperatures approaching 2200°C.

Silicon was given its name in 1831 by Scottish chemist Thomas Thomson. He retained part of Berzelius’s name, from ‘silicis,’ meaning flint. Flint is a type of hard rock that was used by many early civilizations to make tools and weapons.

In 1854, Henri Deville produced crystalline silicon for the first time. He first prepared crystalline silicon, the second allotropic form of the element.

1954 witnessed the creation of the first commercial silicon transistor. The creation of semiconductors most commonly uses sand as starting material because of its high percentage of silicon.
Discovery of silicon

History discovery of plutonium

Plutonium was first synthetically produced in December 1940 at the University of California at Berkeley, California, by Glenn Seaborg, Arthur Wahl, Joseph Kennedy, and Edwin McMillan. They produced it by bombarding uranium-238 with deuterium nuclei (α-particles) in the 60-inch cyclotron of the Berkeley Radiation Laboratory at the University of California, Berkeley, but the discovery was kept secret. The element was named after the then planet Pluto.

This first produced neptunium-238 with a half-life of two days, and this decayed by beta emission to form element 94 (plutonium). Within a couple of months element 94 had been conclusively identified and its basic chemistry shown to be like that of uranium.

The researchers submitted news of the discovery and the proposed name and symbol to the journal Physical Review but withdrew it when it became apparent plutonium could be used for an atomic bomb. This experiment wasn't shared with the rest of the scientific community until 1946, after World War II.

Early research on plutonium was carried out secretly at the University of Chicago’s Metallurgical Laboratory. A trace quantity of plutonium was isolated and measured for the first time on August 20, 1942. During this time, the nuclear properties of plutonium-239 were also studied.

To begin with, the amounts of plutonium produced were invisible to the eye, but by August 1942 there was enough to see and weigh, albeit only 3 millionths of a gram. In October 1943, construction began on a revolutionary plutonium production reactor in Hanford, WA. The B Reactor, as it came to known, was completed in March 1945 and began producing plutonium for the implosion-type atomic bomb.

Plutonium is used in both nuclear reactors and nuclear weapons. By 1945 the Americans had several kilograms, and enough plutonium to make three atomic bombs, one of which exploded over Nagasaki in August 1945.

Plutonium-238 was used on the Apollo-14 lunar flight in 1971 to power seismic devices and other equipment left on the Moon, and it was also the power supply of the two Voyager supercraft launched in 1977.
History discovery of plutonium

Discovery of germanium

Germanium was discovered by Clemens A. Winkler (1838-1902) at Freiberg, Germany in 1886.

Its existence had been predicted by Mendeleyev who saw that there had to be an element below silicon and above tin in group IV of his periodic table.  In his report on the Periodic of the Chemical Elements published in 1869 Dmitri Ivanovich Mendeleyev predicted the existence of several unknown chemical elements.

Winkler obtained his germanium from the mineral argyrodite, which is Ag8GeS6. At that time, Winkler was working at the Freiberg University of Mining and Technology. The new mineral proved to be combination of silver, sulfur and a new element.

After a careful examination, Winkler was able to isolate a new element in the elemental state.

Winkler named the new element germanium (from Latin word, Germania for Germany) in honor of his homeland.

Germanium did not become economically significant until after 1945, when its properties as a semiconductor were recognized as being very useful in electronics.

Germanium diode

However, during World War II, small amounts of germanium had begun to be used in some special electronic devices, mostly diodes. The development of the germanium transistor in 1948 opened the door to countless application of solid state electronics.
Discovery of germanium