Effects from a 90-day inhalation toxicity study with cerium oxide and barium sulfate nanoparticles in rats.

See more Barium products. Barium (atomic symbol: Ba, atomic number: 56) is a Block S, Group 2, Period 6 element with an atomic weight of 137.27. The number of electrons in each of barium's shells is [2, 8, 18, 18, 8, 2] and its electron configuration is [Xe] 6s². Barium is a member of the alkaline-earth metals. The barium atom has a radius of 222 pm and a Van der Waals radius of 268 pm. Barium was discovered by Carl Wilhelm Scheele in 1772 and first isolated by Humphry Davy in 1808. In its elemental form, barium is a soft, silvery-gray metal. Industrial applications for barium include acting as a "getter," or unwanted gas remover, for vacuum tubes, and as an additive to steel and cast iron. Barium is also alloyed with silicon and aluminum in load-bearing alloys. The main commercial source of barium is the mineral barite (BaSO₄); it does not occur naturally as a free element . The name barium is derived from the Greek word "barys," meaning heavy.

See more Cerium products. Cerium (atomic symbol: Ce, atomic number: 58) is a Block F, Group 3, Period 6 element with an atomic weight of 140.116. The number of electrons in each of cerium's shells is 2, 8, 18, 19, 9, 2 and its electron configuration is [Xe]4f² 6s². The cerium atom has a radius of 182.5 pm and a Van der Waals radius of 235 pm. In its elemental form, cerium has a silvery white appearance. Cerium is the most abundant of the rare earth metals. It is characterized chemically by having two valence states, the +3 cerous and +4 ceric states. The ceric state is the only non-trivalent rare earth ion stable in aqueous solutions. It is therefore strongly acidic and oxidizing, in addition to being moderately toxic.The cerous state closely resembles the other trivalent rare earths. Cerium is found in the minerals allanite, bastnasite, hydroxylbastnasite, monazite, rhabdophane, synchysite and zircon. Cerium was discovered by Martin Heinrich Klaproth, Jöns Jakob Berzelius, and Wilhelm Hisinger in 1803 and first isolated by Carl Gustaf Mosander in 1839. The element was named after the asteroid Ceres, which itself was named after the Roman god of agriculture.

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.