Properties of metals, metalloids and nonmetals one or two properties very different from the expected norm, or that are otherwise notable. Sodium, potassium, rubidium, caesium, barium, platinum, gold Manganese Iron, cobalt, nickel, gadolinium, terbium, dysprosium, holmium, erbium, thulium Iridium Gold Mercury Lead Bismuth Uranium Plutonium Boron Boron, antimony Silicon Arsenic Antimony Hydrogen Helium Carbon Phosphorus Iodine Properties of metals, metalloids and nonmetals Metals appear lustrous (beneath any patina); form mixtures (alloys) when combined with other metals; tend to lose or share electrons when they react with other substances; and each forms at least one predominantly basic oxide. Most metals are silvery looking, high density, relatively soft
Arsenic though these are not ionic compounds containing the As ion as the formation of such an anion would be highly endothermic and even the group 1 arsenides have properties of intermetallic compounds. Like germanium, selenium, and bromine, which like arsenic succeed the 3d transition series, arsenic is much less stable in the group oxidation state of +5 than its vertical neighbors phosphorus and antimony, and hence arsenic pentoxide and arsenic acid are potent oxidizers. Compounds of arsenic resemble in some respects those of phosphorus which occupies the same group (column) of the periodic table. The most common oxidation states for