Holmium Arsenate

See more Arsenic products. Arsenic (atomic symbol: As, atomic number: 33) is a Block P, Group 15, Period 4 element with an atomic radius of 74.92160. The number of electrons in each of arsenic's shells is 2, 8, 18, 5 and its electron configuration is [Ar] 3d¹⁰ 4s² 4p³. The arsenic atom has a radius of 119 pm and a Van der Waals radius of 185 pm. Arsenic was discovered in the early Bronze Age, circa 2500 BC. It was first isolated by Albertus Magnus in 1250 AD. In its elemental form, arsenic is a metallic grey, brittle, crystalline, semimetallic solid. Arsenic is found in numerous minerals including arsenolite (As₂O₃), arsenopyrite (FeAsS), loellingite (FeAs₂), orpiment (As₂S₃), and realgar (As₄S₄). Arsenic has numerous applications as a semiconductor and other electronic applications as indium arsenide, silicon arsenide and tin arsenide. Arsenic is finding increasing uses as a doping agent in solid-state devices such as transistors.

See more Holmium products. Holmium (atomic symbol: Ho, atomic number: 67) is a Block F, Group 3, Period 6 element with an atomic radius of 164.93032. The number of electrons in each of Holmium's shells is [2, 8, 18, 29, 8, 2] and its electron configuration is [Xe] 4f¹¹ 6s². The holmium atom has a radius of 176 pm and its Covalent radius is 192±7 pm. Holmium was first discovered by Marc Delafontaine in 1878. In its elemental form, holmium has a silvery white appearance. It is relatively soft and malleable. It is stable in dry air at room temperature but rapidly oxidizes at elevated temperatures and in moist air. Holmium has unusual magnetic properties. Its name is derived from the Latin word Holmia meaning Stockholm.