Nobelium Facts – Symbol No or Atomic Number 102

Nobelium is a synthetic radioactive element with the atomic number 102 and symbol No. It is a member of the actinide series and has no stable isotopes. Nobelium does not occur naturally. Because of its short half-life and rarity, nobelium has no practical applications outside of scientific research.

Key Facts: Nobelium

• Nobelium (No) is a synthetic, radioactive actinide with atomic number 102.
• It was named after Alfred Nobel.
• Unlike most actinides, nobelium favors the +2 oxidation state over +3.
• Its +2 oxidation state makes it chemically behave more like barium and the rare earths than the other actinides.
• It is produced by bombarding curium-248 with carbon-12 or carbon-13 nuclei.
• The most stable isotope, No-259, has a half-life of about 58 minutes.
• Nobelium has no known practical applications due to its short-lived nature.
• Its chemistry helps scientists study relativistic effects in heavy elements.

History of Discovery and Naming

The discovery of nobelium was a subject of significant controversy, with competing claims from research groups in Sweden, the Soviet Union, and the United States. Over time, a clearer picture emerged, leading to the official credit being awarded to the Soviet team at Dubna (JINR) in 1965.

Early (Incorrect) Claim – Sweden (1957)

The first reported discovery of element 102 came from scientists at the Nobel Institute of Physics in Stockholm, Sweden, in 1957. They claimed to have synthesized the element by bombarding curium-244 with carbon-13 ions. Based on their findings, they proposed the name nobelium (No) in honor of Alfred Nobel. However, further investigations revealed that their identification was incorrect, and the claim was discredited.

First Synthesis Attempt – Soviet Union (1958)

In 1958, a team at the Joint Institute for Nuclear Research (JINR) in Dubna, USSR, led by Georgy Flerov, attempted producing element 102 by bombarding uranium-238 with neon-22 ions. Although they reported success, their identification of the new element was questioned due to inconsistent decay data. At the time, there was no definitive proof that element 102 had been created.

Successful Synthesis and Characterization – Soviet Union (1965) and United States (1966)

In 1965, the Dubna team revisited their experiments, using a different reaction:

₉₆²⁴²Cm + ₇¹⁵N → ₁₀₂²⁵⁶No + n

This time, their data provided stronger evidence that they had successfully synthesized nobelium-256. Their findings were more reliable than their previous work, and they accurately characterized the element’s properties, leading to their official recognition as the discoverers of nobelium.

Shortly after, in 1966, scientists at the Lawrence Berkeley National Laboratory (LBNL) in California, led by Albert Ghiorso, Glenn Seaborg, and Torbjørn Sikkeland, confirmed the existence of nobelium by synthesizing and characterizing isotopes No-254, No-255, and No-256. Their data validated the Dubna team’s findings and provided a more comprehensive understanding of the element’s behavior.

Naming of Nobelium

Despite the incorrect Swedish claim, the name “nobelium” was widely used and became accepted internationally. In 1997, the International Union of Pure and Applied Chemistry (IUPAC) officially recognized Dubna (JINR) as the discoverers but retained the name “nobelium” in honor of Alfred Nobel.

Synthesis and Isolation

Since nobelium is a synthetic element, it results from nuclear reactions. The most common method involves bombarding curium-248 with carbon-12 or carbon-13 nuclei in a particle accelerator. For example, one viable nuclear reaction is:

₉₆²⁴⁸Cm + ₆¹²C → ₁₀₂²⁵⁶No + 4n

Separation of nobelium isotopes involves chemical techniques, typically by exploiting their behavior in aqueous solution.

Periodic Table Location and Element Group

As an actinide, nobelium is a member of the f-block, which contains elements characterized by the filling of their 5f orbitals. It is chemically similar to other late actinides, such as fermium and mendelevium. Nobelium is in period 7 at the bottom of the periodic table, between mendelevium and lawrencium and directly below ytterbium.

Predicted Appearance

Since only microscopic amounts of nobelium have ever been produced, its macroscopic appearance is unknown. However, based on its position in the periodic table, nobelium is likely a silvery-white metal that oxidizes to a darker color in air.

Oxidation States

Nobelium primarily exhibits oxidation states of +2 and +3, with +2 being the most stable in aqueous solution, unlike most actinides that favor the +3 state. This behavior arises from:

• A fully filled 5f¹⁴ configuration, which is more stable than an unfilled 5f¹³ state.
• Relativistic effects, which reduce 5f electron participation in bonding.
• Experimental confirmation, which shows No²⁺ is dominant in aqueous chemistry.

This makes nobelium the only actinide chemically similar to alkaline earth metals, behaving more like barium and radium than its neighboring actinides.

Isotopes of Nobelium

Nobelium has no stable isotopes. The most well-studied isotopes include:

The longest-lived isotope, No-259, has a half-life of 58 minutes, making detailed experimentation challenging.

Uses of Nobelium

Due to its short half-life and extreme rarity, nobelium has no commercial or industrial applications. Its primary use is scientific research, particularly in studying the properties of heavy actinides and their behavior in chemical reactions.

Chemistry and Compounds

Nobelium compounds include nobelium(II) chloride (NoCl₂) and nobelium(III) chloride (NoCl₃). Complexing with chloride ions is on par with barium. Complexing with acetate, citrate, and oxalate ions most closely resembles behavior by strontium.

Biological Role, Health Effects, and Toxicity

• Biological Role: Nobelium has no known biological function.
• Toxicity: As a radioactive element, nobelium is highly hazardous due to its emission of alpha particles.
• Health Effects: Nobelium exposure is limited to scientific settings, and its radioactivity makes it dangerous to human health.

Key Nobelium Facts Table

Interesting Nobelium Facts

1. Nobelium is one of the few actinides where the +2 oxidation state is more stable than +3, similar to europium.
2. It was incorrectly “discovered” multiple times before being properly identified.
3. Due to its short half-life, a visible sample of nobelium metal may never exist.
4. Unlike most actinides, nobelium does not behave like a transition metal in solution.
5. The element takes its name after Alfred Nobel, but he had no involvement in its discovery.

References

• Fournier, Jean-Marc (1976). “Bonding and the electronic structure of the actinide metals”. Journal of Physics and Chemistry of Solids. 37 (2): 235–244. doi:10.1016/0022-3697(76)90167-0
• Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
• Lide, David R., ed. (2003). CRC Handbook of Chemistry and Physics (84th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0484-9.
• Oganessian, Yu. Ts.; Rykaczewski, K. P. (2015). “A beachhead on the island of stability”. Physics Today. 68 (8): 32–38. doi:10.1063/PT.3.2880
• Silva, Robert J. (2011). “Chapter 13. Fermium, Mendelevium, Nobelium, and Lawrencium”. In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements. Netherlands: Springer. doi:10.1007/978-94-007-0211-0_13. ISBN 978-94-007-0210-3.