Rutherfordium (Rf)
Element 104 · Transition metal · Solid at 25 °C · Group 4, Period 7
Rutherfordium is a synthetic element, produced one atom at a time in particle accelerator experiments. Its isotopes decay within moments, so none of its bulk properties have ever been measured directly — the values chemists cite for it are theoretical predictions. It is named for physicist Ernest Rutherford, the father of nuclear physics.
On the periodic table, rutherfordium sits in group 4 in period 7. It is one of 38 elements classified as a transition metal, and at room temperature (25 °C) it is a solid.
Transition metals occupy the wide d-block in the middle of the table. As a family they are hard, dense, high-melting metals that conduct heat and electricity well. Their partly filled d-orbitals let many of them take several oxidation states, form vividly colored compounds, and act as catalysts — which is why so much of industry, and so much of biology, runs on this block.
Properties of rutherfordium
| Atomic number (Z) | 104 |
|---|---|
| Symbol | Rf |
| Atomic mass | (267) (mass number of the most stable isotope; this element has no standard atomic weight) |
| Category | Transition metal |
| Group | 4 |
| Period | 7 |
| Block | d-block |
| Metal / nonmetal | Metal |
| State at 25 °C | Solid |
| Electron configuration | [Rn] 5f14 6d2 7s2 |
| Electronegativity (Pauling) | — |
| Melting point | — |
| Boiling point | — |
| Density | — |
Position in the periodic table
Rutherfordium shares group 4 with Titanium (Ti), Zirconium (Zr), Hafnium (Hf). Elements in the same group have the same number of outer electrons, so they tend to behave alike chemically — comparing them is one of the fastest ways to see periodic trends in action.
Physical properties
No melting point, boiling point, or density has been measured for rutherfordium: too few atoms have ever existed at once. Published figures for these properties are theoretical estimates, so this site shows them as dashes rather than presenting predictions as data.
Data notes
The atomic mass is shown in parentheses because this element has no standard atomic weight; the number given is the mass number of its most stable known isotope.
The state and electron configuration listed for this element are predicted values — it has never been produced in quantities large enough to observe directly.
See also: the interactive periodic table, how to read the periodic table, periodic trends.