in seconds. All the remaining isotopes have half-lives measured in milliseconds, with the exception of the shortest-lived isotope, 261mSg, with a half-life of only 92 microseconds. The proton-rich isotopes from 258Sg to 261Sg were directly produced by cold fusion; all heavier isotopes were produced from the repeated alpha decay of the heavier elements hassium, darmstadtium, and flerovium, with the exceptions of the isotopes 263mSg, 264Sg, 265Sg, and 265mSg, which were directly produced by hot fusion through irradiation of actinide targets. The twelve isotopes of seaborgium have half-lives ranging from 92 microseconds for 261mSg to 14 minutes for 269Sg. Predicted properties Very few properties of seaborgium or its compounds have been measured; this is due to its extremely limited and expensive production and the fact that seaborgium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, but properties of seaborgium metal remain unknown and only predictions are available. Physical Seaborgium is expected to be a solid under normal conditions and assume a body-centered cubic crystal structure, similar to its lighter congener tungsten. Early predictions estimated that it should be a very heavy metal with density around 35.0 g/cm3, but calculations in 2011 and 2013 predicted a somewhat lower value of 23–24 g/cm3. Chemical Seaborgium is the fourth member of the 6d series of transition metals and the heaviest member of group 6 in the periodic table, below chromium, molybdenum, and tungsten. All the members of the group form a diversity of oxoanions. They readily portray their group oxidation state of +6, although this is highly oxidising in the case of chromium, and this state becomes more and more stable to reduction as the group is descended: indeed, tungsten is the last of the 5d transition metals where all four 5d electrons participate in metallic bonding. As such, seaborgium should have +6 as its most stable oxidation state, both in the gas phase and in aqueous solution, and this is the only oxidation state that is experimentally known for it; the +5 and +4 states should be less stable, and the +3 state, the most common for chromium, would be the least stable for seaborgium. This stabilisation of the highest oxidation state occurs in the early 6d elements because of the similarity between the energies of the 6d and 7s orbitals, since the 7s orbitals are relativistically stabilised and the 6d orbitals are relativistically destabilised. This effect