What Is Mendelevium?
Mendelevium is a chemical element with the symbol Md and atomic number 101, part of the radioactive actinide series.
Named in honor of Dmitri Mendeleev, creator of the periodic table.
As a actinide in Period 7 and Group 3 (Transition Metals), mendelevium's placement on the table reflects its electron configuration of [Rn] 5f¹³ 7s², which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Mendelevium is located in Period 7, the bottom row of the standard periodic table, consisting largely of radioactive and synthetic elements.
Within that row, mendelevium 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
Mendelevium has an atomic mass of (258) u and a density of ~10.3 g/cm³. Its melting point is 827°C and its boiling point is ~1100°C.
Mendelevium is radioactive, like every other member of the actinide series, with a nucleus prone to spontaneous decay.
Electron Configuration Explained
Mendelevium's electron configuration is [Rn] 5f¹³ 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 mendelevium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Mendelevium was formally discovered in 1955, 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 Mendelevium Used For?
Mendelevium's specific properties make it useful in several applications, including:
- Research only
- Nuclear chemistry
- Scientific study
- No practical uses
- Academic research
These uses reflect mendelevium'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 Mendelevium
- Mendelevium was synthesized near the periodic table's 100th anniversary in 1955.
- Mendelevium is element number 101 on the periodic table, in Period 7 and Group 3.
- Its standard atomic mass is (258) u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Mendelevium's atomic number?
Mendelevium has atomic number 101.
What is Mendelevium's chemical symbol?
Mendelevium's symbol is Md.
What group and period is Mendelevium in?
Mendelevium is in Period 7, Group 3 (Transition Metals).
What is Mendelevium's atomic mass?
Mendelevium's standard atomic mass is (258) u.