What Is Curium?

With symbol Cm and atomic number 96, Curium is a member of the actinides, the bottom row of the standard periodic table.

Named after Marie and Pierre Curie. Has powered space exploration via RTGs.

As a actinide in Period 7 and Group 3 (Transition Metals), curium's placement on the table reflects its electron configuration of [Rn] 5f⁷ 6d¹ 7s², which governs its bonding behavior and the type of compounds it typically forms.

Position on the Periodic Table

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

Within that row, curium 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

Curium has an atomic mass of (247) u and a density of 13.51 g/cm³. Its melting point is 1345°C and its boiling point is 3110°C.

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

Electron Configuration Explained

Curium's electron configuration is [Rn] 5f⁷ 6d¹ 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 curium's chemical reactivity and the type of bonds it forms with other elements.

History & Discovery

Curium was formally discovered in 1944, 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 Curium Used For?

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

  • Space power (RTG)
  • Alpha particle sources
  • Nuclear research
  • Neutron sources
  • Scientific study

These uses reflect curium'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 Curium

  • Curium was named after Marie and Pierre Curie — the only married couple to both win Nobel Prizes.
  • Curium is element number 96 on the periodic table, in Period 7 and Group 3.
  • Its standard atomic mass is (247) u, calculated from the natural abundance of its isotopes.

Frequently Asked Questions

What is Curium's atomic number?
Curium has atomic number 96.

What is Curium's chemical symbol?
Curium's symbol is Cm.

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

What is Curium's atomic mass?
Curium's standard atomic mass is (247) u.