Lead-Sulfide-Selenide Quantum Dots and Gold-Copper Alloy Nanoparticles Augment the Light-Harvesting Ability of Solar Cells.

See more Selenium products. Selenium (atomic symbol: Se, atomic number: 34) is a Block P, Group 16, Period 4 element with an atomic radius of 78.96. The number of electrons in each of Selenium's shells is 2, 8, 18, 6 and its electron configuration is [Ar] 3d¹⁰ 4s² 4p⁴. The selenium atom has a radius of 120 pm and a Van der Waals radius of 190 pm. Selenium is a non-metal with several allotropes: a black, vitreous form with an irregular crystal structure three red-colored forms with monoclinic crystal structures and a gray form with a hexagonal crystal structure, the most stable and dense form of the element. One of the most common uses for selenium is in glass production the red tint that it lends to glass neutralizes green or yellow tints from impurities in the glass materials. Selenium was discovered and first isolated by Jöns Jakob Berzelius and Johann Gottlieb Gahn in 1817. The origin of the name Selenium comes from the Greek word "Selênê," meaning moon.

See more Copper products. Copper (atomic symbol: Cu, atomic number: 29) is a Block D, Group 11, Period 4 element with an atomic weight of 63.546. The number of electrons in each of copper's shells is 2, 8, 18, 1 and its electron configuration is [Ar]3d¹⁰ 4s¹. The copper atom has a radius of 128 pm and a Van der Waals radius of 186 pm. Copper was first discovered by Early Man prior to 9000 BC. In its elemental form, copper has a reddish-orange metallic and lustrous appearance. Of all pure metals, only silver has a higher electrical conductivity. The origin of the word copper comes from the Latin word 'cuprium' which translates as "metal of Cyprus," as the Mediterranean island of Cyprus was known as an ancient source of mined copper..

See more Gold products. Gold (atomic symbol: Au, atomic number: 79) is a Block D, Group 11, Period 6 element with an atomic weight of 196.966569. The number of electrons in each of Gold's shells is 2, 8, 18, 32, 18, 1 and its electron configuration is [Xe]4f¹⁴² 5d¹⁰ 6s¹. The gold atom has a radius of 144 pm and a Van der Waals radius of 217 pm. Gold was first discovered by Early Man prior to 6000 B.C. In its elemental form, gold has a metallic yellow appearance. Gold is a soft metal and is usually alloyed to give it more strength. It is a good conductor of heat and electricity, and is unaffected by air and most reagents. It is one of the least reactive chemical elements. Gold is often found as a free element and with silver as a gold-silver alloy. Less commonly, it is found in minerals as gold compounds, usually with tellurium.

See more Sulfur products. Sulfur (or Sulphur) (atomic symbol: S, atomic number: 16) is a Block P, Group 16, Period 3 element with an atomic radius of 32.066. The number of electrons in each of Sulfur's shells is 2, 8, 6 and its electron configuration is [Ne] 3s² 3p⁴. In its elemental form, sulfur has a light yellow appearance. The sulfur atom has a covalent radius of 105 pm and a Van der Waals radius of 180 pm. In nature, sulfur can be found in hot springs, meteorites, volcanoes, and as galena, gypsum, and epsom salts. Sulfur has been known since ancient times but was not accepted as an element until 1777, when Antoine Lavoisier helped to convince the scientific community that it was an element and not a compound.

See more Lead products. Lead (atomic symbol: Pb, atomic number: 82) is a Block P, Group 14, Period 6 element with an atomic radius of 207.2. The number of electrons in each of Lead's shells is [2, 8, 18, 32, 18, 4] and its electron configuration is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². The lead atom has a radius of 175 pm and a Van der Waals radius of 202 pm. In its elemental form, lead has a metallic gray appearance. Lead occurs naturally as a mixture of four stable isotopes: ²⁰⁴Pb (1.48%), ²⁰⁶Pb (23.6%), ²⁰⁷Pb (22.6%), and ²⁰⁸Pb (52.3%). Lead is obtained mainly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim are other common lead containing minerals. Lead does occur as a free element in nature, but it is rare. It is a dense, soft metal that is very resistant to corrosion and poorly conductive compared to other metals. Its density and low melting point make it useful in applications such as electrolysis and industrial materials.