Einsteinium
Actinide · Period 7 · f-block
Born in the first hydrogen bomb blast, and named for Einstein
- Atomic mass
- 252 u
- State at 25 °C
- Solid
- Electronegativity
- 1.3
- Melting point
- 859.9 °C
- Boiling point
- 995.9 °C
- Configuration
- [Rn] 5f11 7s2
Nucleus drawn at reduced count for clarity. Drag to rotate.
Einsteinium, explained
Video lesson in production
Bhavya’s explainer for this element will play here.
Overview
Einsteinium is a soft, silvery, radioactive actinide metal with the configuration 5f11 7s2. It usually forms Es3+, but the +2 state is more stable than for earlier actinides, as the 5f electrons become harder to remove. Its chemistry resembles holmium in the lanthanide row. Einsteinium is the heaviest element ever made in amounts large enough to see; its most-produced isotope, einsteinium-253, releases about a thousand watts of heat per gram, so samples glow and their crystal structure is steadily damaged by their own radiation.
The longest-lived isotope, einsteinium-252, has a half-life of 472 days, but it is hard to make. Most studies use einsteinium-253 (20.5 days) or einsteinium-254 (276 days), made in tiny amounts by neutron irradiation of curium and californium. In 2021, chemists at Berkeley used just 233 nanograms of einsteinium-254 to measure the length of an einsteinium bond for the first time. Its main use is as a target: bombarding einsteinium-253 with alpha particles produced the first atoms of mendelevium in 1955.
Discovery
Einsteinium was found in debris from Ivy Mike, the first hydrogen bomb test, at Enewetak Atoll on 1 November 1952. Albert Ghiorso's team at Berkeley, working with Argonne and Los Alamos, identified about 200 atoms of element 99 on filter papers flown through the mushroom cloud. The work was classified until 1955. The element was named after Albert Einstein, who died in April 1955, before the name was published.
- Where it’s found
- Einsteinium does not occur in nature; milligram quantities at most have been produced, mainly in Oak Ridge's High Flux Isotope Reactor.
- What it’s used for
- Synthesis of heavier elements
- Actinide chemistry research
- Nuclear physics studies
- Self-irradiation studies
- In living things
- Einsteinium has no biological role; any absorbed einsteinium would deposit in bone and be highly radiotoxic.
- Safety
- Intensely radioactive and self-heating; only microgram to nanogram amounts exist, handled in specialist hot cells.
How it compares
Where Einsteinium sits among all 118 elements on the trends that shape the table.
- Electronegativity1.3Pauling
#62 of 100 elements with data
- Ionization energy619kJ/mol
#62 of 104 elements with data
- Atomic radiusNo data
Not measured for this element
- Electron affinity-28.6kJ/mol
#92 of 109 elements with data
- Density8.84g/cm³
#49 of 114 elements with data
- Melting point1,130K
#56 of 110 elements with data
- Density
- 8.84 g/cm³
- Atomic radius
- —
- Covalent radius
- —
- Molar heat
- —
- Appearance
- silver-colored
- Discovered by
- Lawrence Berkeley National Laboratory
Inside the atom
99 electrons arranged in 7 shells: 2 · 8 · 18 · 32 · 29 · 8 · 2.
Orbital diagram
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f11 · shorthand [Rn] 5f11 7s2
- 1s2
- 2s2
- 2p6
- 3s2
- 3p6
- 4s2
- 3d10
- 4p6
- 5s2
- 4d10
- 5p6
- 6s2
- 4f14
- 5d10
- 6p6
- 7s2
- 5f11
Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Einsteinium bonds.
Signature reactions
The chemistry Einsteinium is known for.
Nuclear · Rapid neutron capture and beta decay
Formation in Ivy Mike
Uranium-238 absorbed 15 neutrons almost instantly to form uranium-253, which then underwent seven beta decays to reach einsteinium-253. This is a miniature version of the r-process that makes heavy elements in neutron-star mergers.
Conditions: intense neutron flux of a thermonuclear explosion
Nuclear · Alpha bombardment
Making mendelevium
Alpha particles fused with einsteinium-253, and the compound nucleus emitted one neutron to give mendelevium-256. This 1955 experiment identified a new element atom by atom for the first time.
Conditions: alpha beam on an einsteinium target
Nuclear · Alpha decay
Alpha decay of einsteinium-253
Einsteinium-253 emits an alpha particle to become berkelium-249. The rapid decay means any einsteinium sample steadily fills with berkelium and then californium.
Conditions: spontaneous; half-life 20.5 days
Where you’ll meet it
Ivy Mike
The Ivy Mike hydrogen bomb test of 1952 created the first einsteinium.
Photo: Wikimedia Commons
Albert Einstein
Einsteinium honours Albert Einstein, who died months before its name was announced.
Photo: Wikimedia Commons
Enewetak Atoll
Enewetak Atoll in the Marshall Islands was the site of the Ivy Mike test.
Photo: Wikimedia Commons
Los Alamos National Laboratory
Los Alamos scientists helped analyse the Ivy Mike debris in which einsteinium was found.
Photo: Wikimedia Commons
Research
No research on Einsteinium yet
When Bhavya publishes a project that studies Einsteinium, it will be linked here.