Fermium
Definition and meaning of Fermium in chemistry.
![Fermium element card: symbol Fm, atomic number 100, atomic mass [257], electron configuration [Rn] 5f¹² 7s², oxidation states +3, Actinide, f-block, period 7, solid at room temperature.](/assets/images/terms/fermium-chemical-element.webp)
Fermium is a human-made radioactive element with the symbol Fm and atomic number 100. This highly unstable metal belongs to the actinide series on the periodic table. It is the heaviest element scientists can make by firing neutrons at lighter elements.
In more detail
Fermium is a highly radioactive metal that does not exist in nature today. Scientists have made the entire global supply of it through nuclear reactions. Its chemical traits closely match other heavy metals in the actinide series.
Fermium usually shows a +3 oxidation state when dissolved in water. This state tells us how many electrons it uses to bond. Scientists can also force it into a less stable +2 state using special chemicals.
Fermium has a very short half-life and breaks down quickly. A half-life is the time it takes for half of the atoms to decay. Because it decays so fast, scientists can only make tiny amounts at a time.
In fact, no one has ever gathered enough pure fermium to actually see it. This extreme rarity makes testing its physical traits very hard. Most of what we know about solid fermium comes from math and theory.
Fermium sits in the f-block right after einsteinium and right before mendelevium. Scientists first found this element in the radioactive ash of a nuclear test. This 1952 test was the first successful explosion of a hydrogen bomb. Today, researchers make fermium by trapping extra neutrons inside a special nuclear reactor.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Fm |
| Atomic number | 100 |
| Atomic mass | [257] u |
| Category | Actinide |
| Year discovered | 1952 in thermonuclear fallout |
| Discoverer | Albert Ghiorso and co-workers |
Researchers use fermium-257 in special experiments to study heavy atomic nuclei. This specific isotope also serves as a starting material to make even heavier elements. Scientists study these heavy atoms to find the final limits of the periodic table.
Frequently asked questions
Can fermium be found anywhere in natural environments?
No, fermium is completely human-made today. It is only produced in nuclear reactors or particle accelerators. However, trace amounts likely existed on Earth billions of years ago.
What is the most stable isotope of fermium?
Fermium-257 is the most stable known type of this element. It has a half-life of about 100.5 days. After this time, half of it breaks down by alpha decay or spontaneous splitting.
Related terms
Sources & references
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