Discovered | Name | Characteristics

Einsteinium is a member of the actinide series, which stretches from actinium (Ac) to lawrencium (Lr). Einsteinium is a synthetic element; none occurs naturally on earth.

Albert Ghiorso and his coworkers (including Glenn Seaborg) first detected the element in the residue of the first thermonuclear or hydrogen bomb, which was exploded in 1952. It is produced in a chain of reactions beginning with uranium--238; einsteinium is the result of successive neutron captures followed by beta decay.

238U + 15 1n 253Es + 7 b

The element is named in honor of Albert Einstein.

Since it is not possible to set off a hydrogen bomb if you want a few atoms of einsteinium, physicists have devised a 5-step "laboratory" synthesis beginning with plutonium--239.

At least 14 isotopes of Es are known, ranging from mass numbers of 243 to 256. The most stable isotope is 254Es, which has a half-life of about 275 days.

Little is known about its chemistry. However, it is thought that its compounds have oxidation numbers of +2 and +3, with +3 being the more stable.