Rutherfordium (104)

Rutherfordium is a synthetic element that is not present in the environment at all. It has no observable uses to date.

Name: Rutherfordium Symbol: Rf Atomic number: 104 Atomic weight: [ 265 ] Standard state: presumably a solid at 298 K CAS Registry ID: 53850-36-5

Group in periodic table: 4 Group name: (none) Period in periodic table: 7 Block in periodic table: d-block Color: unknown, but probably metallic and silvery white or grey in appearance Classification: Metallic

Historical information

Rutherfordium was discovered in 1969 by scientists at Dubna in Russia, who claimed discovery of element 104 and suggested the name Kurchatovium (Symbol Ku) for the element, in honor of Igor Vasilevich Kurchatov (1903-1960), the late Head of Soviet Nuclear Research.  Their experiments involved the collision reactions between ²⁴²Pu and ²²Ne ions.
Also in 1969 an American group at Berkeley (California) in the USA reported isotopes of Element 104.  Their experiments involved reaction high energy collisions between ²⁴⁹Cf and ¹²C.  The American group also indicated that they were unable to reproduce the earlier Russian synthesis from1964.  The American group proposed for the new element the name Rutherfordium (symbol Rf), in honor of Ernest R. Rutherford, the New Zealand physicist. He is considered to be the “father” of nuclear physics.  Rutherfordium is now the preferred IUPAC name – only since 1997! Funny how quickly things move in the realm of the IUPAC.

Rutherfordium is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, ²⁶⁷Rf, has a half-life of approximately 1.3 hours.

In the periodic table of the elements, it is a d-block element and the first of the fourth-row transition elements.  It is a member of the 7th period and belongs to the group 4 elements. Chemistry experiments have confirmed that rutherfordium behaves as the heavier homologue to hafnium in group 4 . The chemical properties of rutherfordium are characterized only partly.  They compare well with the chemistry of the other group 4 elements, even though some calculations had indicated that the element might show significantly different properties due to relativistic effects.

Physical properties

• Melting point: 2400 K (2100 C or 3800 F)
• Boiling point: 5800 K (5500 C or 9900 F)
• Density of solid: 23.2 g cm^-3

Orbital properties

• Ground state electron configuration:  [Rn].5f¹⁴.6d².7s² (tentative)
• Shell structure:  2.8.18.32.32.10.2
• Term symbol:   ³F₂ (tentative)
• Atomic radius: ~150 picometers (pm)
• Ionization energy: 579.9 kJ mol^-1

Isolation

Only very small amounts of element 104, rutherfordium, have ever been made. The first samples were made through nuclear reactions involving fusion of an isotope of plutonium, ²⁴²Pu, with one of neon, ²²Ne.

²²Ne + ²⁴²Pu → ²⁶⁰₁₀₄Rf + 4 ¹n

Isolation of an observable quantity of rutherfordium has never been achieved