Roentgenium

Roentgenium is a synthetic radioactive element with atomic number 111. It is classified as a group 11 transition metal, though its chemistry is difficult to study because only a few atoms have been produced.

Atomic number: The number of protons in an atom’s nucleus, which defines the chemical element. Roentgenium’s 111 protons distinguish it from every other element.
Element synthesis: The creation of chemical elements through nuclear reactions. Roentgenium exists in laboratories because nuclear fusion assembled its nucleus.
Cold fusion (superheavy element synthesis): A heavy-ion fusion approach using near-spherical nuclei and relatively low excitation energy to synthesize heavy elements. This reaction type produced the first reported roentgenium isotopes.
Copper: A group 11 chemical element with atomic number 29 and the symbol Cu. Copper is a stable, extensively studied group 11 metal, unlike roentgenium.
Periodic table: A tabular arrangement of chemical elements ordered by atomic number and recurring chemical properties. Its position places roentgenium among the group 11 metals.
Nuclear fusion: A nuclear reaction in which two atomic nuclei combine to form a heavier nucleus. A fused projectile and target nucleus produced roentgenium in the discovery experiment.
Nuclear shell model: A model of the nucleus in which protons and neutrons occupy quantized energy levels. Shell structure helps explain the relative stability and decay patterns of roentgenium isotopes.
Silver: A group 11 chemical element with atomic number 47 and the symbol Ag. Silver provides a well-characterized group 11 comparison for roentgenium’s predicted properties.
Group 11: The periodic-table group containing copper, silver, gold, and roentgenium. Roentgenium is assigned to this group based on its position and predicted electron structure.
Bismuth: A chemical element with atomic number 83 and the symbol Bi. Bismuth-209 served as the target nucleus in the first reported synthesis.

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