Ununpentium Element Facts

Ununpentium synthesis

Illustration of an accelerated calcium ion speeding into collision with an americium nucleus. Fusion of these nuclei could, theoretically, produce ununpentium. Image: LLNL


Data Zone

Classification: Ununpentium is an ‘other metal’ (presumed)
Atomic weight: (289), no stable isotopes
State: solid (presumed)
Melting point:
Boiling point:
Electrons: 115
Protons: 115
Neutrons in most abundant isotope: 174
Electron shells: 2, 8, 18, 32, 32, 18, 5
Electron configuration: [Rn] 5f14 6d10 7s2 7p3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Specific heat capacity
Heat of fusion
Heat of atomization
Heat of vaporization
1st ionization energy
2nd ionization energy
3rd ionization energy
Electron affinity
Minimum oxidation number
Min. common oxidation no.
Maximum oxidation number
Max. common oxidation no.
Electronegativity (Pauling Scale)
Polarizability volume
Reaction with air
Reaction with 15 M HNO3
Reaction with 6 M HCl
Reaction with 6 M NaOH
Atomic radius
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity
Electrical conductivity
Freezing/Melting point:

Element 115 decay

Heavy elements 113 and 115 may have been made by combining calcium-48 and amercium-243. Image: LLNL

Discovery of Ununpentium

Dr. Doug Stewart

Research scientists at the Joint Institute for Nuclear Research in Dubna, Russia and the Lawrence Livermore National Laboratory (LLNL), California believed they had made element 115, ununpentium, in Dubna, Russia in 2003. The work was a collaboration between science teams led by Yuri Oganessian and Ken Moody.

The reaction was a fusion of element 20 with element 95: calcium-48 with americium-243.

The experiment began on July 14, 2003 and ended on August 10, 2003.

Calcium ions were formed into a beam in a cyclotron (a particle accelerator) and fired at a target layer of americium deposited on titanium foil.

Four atoms of element 115 (ununpentium) may have been produced, which may have alpha decayed producing element 113 (ununtrium). (1)

The researchers believe one atom of ununpentium-287 was made, and three atoms of ununpentium-288 were made.

The International Union of Pure and Applied Chemistry (IUPAC) reviewed the evidence for the discovery of ununpentium for several years. In 2011 they announced that there was insufficient evidence to prove that the element had been made in the cyclotron.

The IUPAC report stated, “the results are encouraging but do not meet the criteria for discovery because of the paucity of events, the lack of connections to known nuclides, and the absence of cross-bombardments.” (2)

As a result of its position in the periodic table ununpentium is expected to be classed as one of the “other metals” and to have similar properties to the metal bismuth.

Too little of the element has been synthesized for this to be confirmed. The joint teams at JINR in Dubna and Lawrence Livermore in California have published evidence for the synthesis of elements 113, 114, 115, 116, 117 and 118.

IUPAC has accepted the discoveries of element 114 (flerovium/ununquadium) and element 116 (livermorium/ununhexium). It has not yet considered the evidence for the discovery of element 117 (ununseptium).

IUPAC requires stronger evidence before it will confirm the synthesis of element 113 (ununtrium), element 115 (ununpentium), or element 118 (ununoctium).

UPDATE: The discovery of elements 113, 115, 117 and 118 was formally accepted on December 30, 2015 by IUPAC and IUPAP, completing the seventh row of the periodic table.

Appearance and Characteristics

Harmful effects:

Ununpentium is harmful due to its radioactivity.


Ununpentium is a synthetic radioactive metal and has only been produced in minute amounts.

Uses of Ununpentium

Ununpentium is of research interest only.

Abundance and Isotopes

Abundance earth’s crust: nil

Abundance solar system: parts per trillion by weight, parts per trillion by moles

Cost, pure: $ per 100g

Cost, bulk: $ per 100g

Source: Ununpentium could theoretically be produced by bombarding 243Am with 48Ca ions in a heavy ion accelerator. IUPAC does not accept there is enough evidence to accept ununpentium as an established element.

Isotopes: Ununpentium may have 4 isotopes, with mass numbers from 287 to 290. None are stable.


1. Lawrence Livermore National Laboratory , Livermore Scientists Team With Russia To Discover Elements 113 and 115.
2. Robert Barber, Paul Karol, Hiromichi Nakahara, Emanuele Vardaci, and Erich Vogt, Discovery of the elements with atomic numbers greater than or equal to 113,. 2011, IUPAC. (pdf download)

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