What Is Fermium?

Fermium is a chemical element with the symbol Fm and atomic number 100, part of the radioactive actinide series.

Also discovered in hydrogen bomb fallout. Named after Enrico Fermi.

As a actinide in Period 7 and Group 3 (Transition Metals), fermium's placement on the table reflects its electron configuration of [Rn] 5f¹² 7s², which governs its bonding behavior and the type of compounds it typically forms.

Position on the Periodic Table

Fermium is located in Period 7, the bottom row of the standard periodic table, consisting largely of radioactive and synthetic elements.

Within that row, fermium sits in Group 3 (Transition Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.

This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.

Physical & Chemical Properties

Fermium has an atomic mass of (257) u and a density of ~9.7 g/cm³. Its melting point is 1527°C and its boiling point is ~1800°C.

Fermium is radioactive, like every other member of the actinide series, with a nucleus prone to spontaneous decay.

Electron Configuration Explained

Fermium's electron configuration is [Rn] 5f¹² 7s², describing how its electrons are distributed across shells and subshells around the nucleus.

Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.

The outermost (valence) electrons shown in this configuration are what ultimately determine fermium's chemical reactivity and the type of bonds it forms with other elements.

History & Discovery

Fermium was formally discovered in 1952, G.T. Seaborg, identified through the careful isolation and analytical techniques typical of that era's chemical research.

Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.

What Is Fermium Used For?

Fermium's specific properties make it useful in several applications, including:

  • Research only
  • Nuclear physics
  • Scientific study
  • No practical uses
  • Academic research

These uses reflect fermium's underlying classification as a actinide, since the same properties that define its category in chemistry also determine where it becomes practically useful.

Fun Facts About Fermium

  • Fermium was named after Enrico Fermi, who built the world's first artificial nuclear reactor in 1942.
  • Fermium is element number 100 on the periodic table, in Period 7 and Group 3.
  • Its standard atomic mass is (257) u, calculated from the natural abundance of its isotopes.

Frequently Asked Questions

What is Fermium's atomic number?
Fermium has atomic number 100.

What is Fermium's chemical symbol?
Fermium's symbol is Fm.

What group and period is Fermium in?
Fermium is in Period 7, Group 3 (Transition Metals).

What is Fermium's atomic mass?
Fermium's standard atomic mass is (257) u.