Rutherfordium (Rf)

Rutherfordium is a synthetic, highly radioactive transition metal. It does not occur in nature and is produced in particle accelerators. Only a few atoms are made at a time, so its bulk properties are largely unknown. Its chemistry is expected to resemble that of hafnium and zirconium.

Atomic Number
104
Atomic Mass
267
Phase (STP)
Solid
Block
D
Electronegativity (Pauling)

Bohr Atomic Model

Protons
104
Neutrons
163
Electrons
104
Identity
Atomic Number104
SymbolRf
NameRutherfordium
Group4
Period7
Position
Period7
Group Label4
Grid X4
Grid Y7
Physical Properties
Atomic Mass (u)267
Density (g/cm³)
Melting Point (K)null K null °C
Boiling Pointnull K null °C
Phase at STPSolid
CategoryTransition Metals
Liquid Density (g/cm³)
Molar Volume (cm³/mol)
Emission Spectrum (nm)
Discovery
English NameRutherfordium
English Pronunciationroo-ther-FER-dee-əm
Latin Name
Latin Pronunciation
Year1964
DiscovererGeorgy Flerov and colleagues and at Dubna, near Moscow, Russia, and independently by Albert Ghiorso and colleagues at Berkeley, California, USA
CountryUSSR & USA
CAS Number53850-36-5
CID Number
RTECS Number
Atomic Properties
Electron ShellK2 L8 M18 N32 O32 P10 Q2
Electron Configuration[Rn] 5f^1^46d^27s^2
Oxidation States+4 +3
Ion ChargeRf⁴⁺ (predicted)
Ionization Potential (eV)6.001
Electronegativity (Pauling)
Electron Affinity (kJ/mol)
Electrons104
Protons104
Neutrons163
ValenceIV
BlockD
Atomic Radius (pm)
Covalent Radius (pm)157
van der Waals Radius (pm)
Thermodynamic Properties
PhaseSOLID
Heat of Fusion (kJ/mol)
Specific Heat (J/g·K)
Thermal Expansion (1/K)
Heat of Vaporization (kJ/mol)
Mechanical Properties
Brinell Hardness
Mohs Hardness
Vickers Hardness
Bulk Modulus (GPa)
Young's Modulus (GPa)
Shear Modulus (GPa)
Poisson Ratio
Sound Speed (m/s)
Refractive Index
Thermal Conductivity (W/m·K)
Electromagnetic Properties
Electrical Conductivity (S/m)
Electrical Type
Magnetic Type
Volume Magnetic Susceptibility
Mass Magnetic Susceptibility
Molar Magnetic Susceptibility
Resistivity (Ω·m)
Superconducting Point (K)
Crystal Properties
StructureHexagonal (hcp) — predicted
SystemHEXAGONAL
Space Group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
Debye Temperature (K)
Nuclear Properties
RadioactiveYes
Half-lifeLongest-lived isotope 267Rf ~ hours
Lifetime
Neutron Cross-section (barn)
Safety Information
Health HazardRadioactive; handle in specialized facilities
Reactivity Hazard
Specific HazardRadioactive
Prevalence
Universe0
Sun0
Oceans0
Human Body0
Earth Crust0
Meteorites


FAQs about Rutherfordium

Rutherfordium (Rf) is a synthetic element with atomic number 104. It is the first member of the 6d transition metals and belongs to Group 4, below titanium (Ti), zirconium (Zr), and hafnium (Hf).

Rf is created atom-by-atom in heavy-ion fusion reactions using particle accelerators. A stylized route uses curium or californium targets bombarded by oxygen or carbon ions; for example:

\(^{248}\mathrm{Cm}(^{18}\mathrm{O},\,x\,n)\,^{266-x}\mathrm{Rf}\)

Products are separated in-flight and identified by their alpha-decay chains and characteristic energies.

Like its congeners Zr and Hf, Rf is expected to prefer the +4 oxidation state. Volatility and extraction experiments with a few atoms suggest the formation of chlorides/oxychlorides analogous to Hf and Zr (e.g., RfCl4, complex anions under strongly chlorinating conditions).

Relativistic calculations and trend arguments support a ground-state configuration close to [Rn] 5f14 6d2 7s2. Participation of 6d/7s (and relativistic effects) guides its Group-4-like chemistry.

Only a few atoms can be produced at a time and they decay quickly. This prevents preparing macroscopic samples to measure properties like density, melting point, or crystal structure. Most information comes from atom-at-a-time chemistry and gas-phase or chromatography studies.

Atoms recoil out of the target and are separated by magnetic/electrostatic filters or gas jets. Identification relies on time-correlated alpha decays and known daughter chains. A simple decay notation is:

\(^{265}\mathrm{Rf} \;\to\; ^{261}\mathrm{No} + \alpha\)

Experiments indicate Rf tetrachloride (and possibly oxychlorides) exhibit volatility trends similar to HfCl4 under comparable conditions. This supports its placement as a true Group-4 analogue in halide chemistry.

Yes. Rf is a radiotoxic heavy metal. Although produced in vanishingly small amounts, all work is done in specialized hot cells or glove boxes with remote handling, HEPA-filtered ventilation, shielding, dosimetry, and compliant radioactive-waste procedures.

Rf was first reported in the late 1960s by teams in Dubna and Berkeley. After a period of naming controversy, the element was officially named Rutherfordium in honor of physicist Ernest Rutherford.

One example route is:

\(^{249}\mathrm{Cf}(^{12}\mathrm{C},\,4n)\,^{257}\mathrm{Rf}\)

Here, the compound nucleus evaporates n neutrons, leaving a specific Rf isotope that is then tracked via its decay chain.