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What is the 119th element?

The 119th element on the periodic table is Ununennium, symbolized as Uue. Ununennium is an extremely radioactive synthetic element that has yet to be discovered in nature. It is considered to be one of the superheavy elements, found on the bottom row of the periodic table past atomic number 104.

Discovery of Ununennium

Ununennium has not yet been synthesized or discovered in nature. It is a hypothetical element that is predicted to have an atomic number of 119 based on the ordering of elements on the periodic table. Theorized properties and characteristics of Ununennium are extrapolated based on trends of other superheavy elements and theoretical models.

The discovery of new superheavy elements is an ongoing effort. Currently, the heaviest element that has been synthesized is oganesson, element 118. Heavier elements beyond oganesson are expected to become increasingly unstable, with decreasing half-lives. However, advancements in nuclear synthesis techniques and detection capabilities continue to push the boundaries of atomic discovery. The eventual synthesis of Ununennium would mark another milestone in expanding the periodic table.

Classification of Ununennium

As an undiscovered element, Ununennium currently has no definitive classification. Based on its predicted properties, Ununennium would be classified as follows:

  • Group: Group 18 (Noble gases)
  • Period: Period 7
  • Block: P-block
  • Category: Noble gas

Ununennium is predicted to be a gaseous noble element, exhibiting very low chemical reactivity like others in its group. However, as a superheavy element, its classification is speculative and subject to change if it is one day synthesized and its properties analyzed.

Properties of Ununennium

Since Ununennium remains undiscovered, its chemical and physical properties are theoretical projections. Some predicted key properties include:

  • Atomic mass: 299 u
  • Melting point: -220.15°F (-140.08°C)
  • Boiling point: -201.27°F (-129.59°C)
  • Density: 0.00475 g/cm3
  • Phase at room temperature: Gas
  • Electron configuration: [Og] 5g18 6f14 7d10 8s2 8p6

Again, these projected properties could change based on future experimental observations. Some models predict Ununennium may display unexpected chemical behavior unlike other group 18 elements. However, a noble gas configuration is considered most likely given current knowledge.

Key Predicted Properties of Ununennium

Property Predicted Value
Atomic mass 299 u
Melting point -220.15°F (-140.08°C)
Boiling point -201.27°F (-129.59°C)
Density 0.00475 g/cm3
Phase at room temperature Gas
Electron configuration [Og] 5g18 6f14 7d10 8s2 8p6

Isotopes of Ununennium

No isotopes of Ununennium have been produced or observed, since the element itself remains undiscovered. The hypothetical isotopes Ununennium-298 and Ununennium-299 are predicted to be the most stable, with half-lives on the order of seconds. Heavier isotopes would likely have decreasing stability and increasingly shorter half-lives.

The predicted decay modes of possible Ununennium isotopes include alpha decay, spontaneous fission, and electron capture. The instability of the element would make it very difficult to study any isotopes produced. Nuclear theorists continue to investigate models and methods to extend the periodic table long enough to synthesize Ununennium isotopes.

Predicted Isotopes of Ununennium

Isotope Half-life Decay mode
Uue-298 ~100 ms Alpha decay
Uue-299 ~1 s Alpha decay
Uue-300 ~300 μs Spontaneous fission

Uses of Ununennium

Currently, Ununennium has no uses, given it has yet to be created or found naturally. As a synthetic superheavy element, it would likely only be produced in very small quantities in nuclear laboratories. Any practical applications of Ununennium would be limited due its radioactive instability.

Potential uses of Ununennium, should stable isotopes be discovered, include:

  • Nuclear research – Studying its nuclear properties would expand knowledge of theoretical island of stability.
  • Lasers – Ununennium plasma could be used as a gain medium in lasers.
  • Quantum computers – Its unique electron structure could be useful for quantum computing.

However, these applications are highly speculative. The primary use of creating Ununennium would likely be to expand the boundaries of the periodic table rather than any technological function.


In summary, Ununennium is the temporary name for the hypothetical chemical element with atomic number 119. It has not yet been successfully synthesized or found naturally occurring. Ununennium is predicted to be an extremely unstable radioactive noble gas, the seventh period’s heaviest element. While predictions can be made about Ununennium’s properties and behavior, its actual characteristics remain unknown. The eventual discovery of element 119 would complete the seventh row of the periodic table and offer insight into the elusive island of stability. Until then, Ununennium exists only in theory, the stuff of nuclear science dreams.