Hierarchical assembly of urchin-like alpha-iron oxide hollow microspheres and molybdenum disulphide nanosheets for ethanol gas sensing.

See more Iron products. Iron (atomic symbol: Fe, atomic number: 26) is a Block D, Group 8, Period 4 element with an atomic weight of 55.845. The number of electrons in each of Iron's shells is 2, 8, 14, 2 and its electron configuration is [Ar] 3d⁶ 4s². The iron atom has a radius of 126 pm and a Van der Waals radius of 194 pm. Iron was discovered by humans before 5000 BC. In its elemental form, iron has a lustrous grayish metallic appearance. Iron is the fourth most common element in the Earth's crust and the most common element by mass forming the earth as a whole. Iron is rarely found as a free element, since it tends to oxidize easily; it is usually found in minerals such as magnetite, hematite, goethite, limonite, or siderite. Though pure iron is typically soft, the addition of carbon creates the alloy known as steel, which is significantly stronger.

See more Molybdenum products. Molybdenum (atomic symbol: Mo, atomic number: 42) is a Block D, Group 6, Period 5 element with an atomic weight of 95.96. The number of electrons in each of molybdenum's shells is [2, 8, 18, 13, 1] and its electron configuration is [Kr] 4d⁵ 5s¹. The molybdenum atom has a radius of 139 pm and a Van der Waals radius of 209 pm. In its elemental form, molybdenum has a gray metallic appearance. Molybdenum was discovered by Carl Wilhelm in 1778 and first isolated by Peter Jacob Hjelm in 1781. Molybdenum is the 54th most abundant element in the earth's crust. It has the third highest melting point of any element, exceeded only by tungsten and tantalum. Molybdenum does not occur naturally as a free metal, it is found in various oxidation states in minerals. The primary commercial source of molybdenum is molybdenite, although it is also recovered as a byproduct of copper and tungsten mining. The origin of the name Molybdenum comes from the Greek word molubdos meaning lead.

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.