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101 Md Mendelevium 258

Mendelevium

ACTINIDE
Bohr Model: Electrons arranged in energy shells around the nucleus.

Mendelevium is a synthetic element with chemical symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities through neutron bombardment of lighter elements. It is the antepenultimate actinide and the ninth transuranic element.

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Quick Facts

Atomic Number 101
Period 7
Group 15
Phase Solid
Appearance Unknown
About Actinides

Actinides are the 15 metallic elements with atomic numbers 89–103. All actinides are radioactive.

History

Discovered By Lawrence Berkeley National Laboratory
Named By Unknown

Physical Properties

Atomic Mass 258
Density N/A g/L
Molar Heat N/A J/(mol·K)
Phase Transition (Melting & Boiling Points)

Mendelevium melts at 1100 K. The boiling point is currently unknown.

Atomic Properties

Electron Config [Rn] 5f13 7s2
Electronegativity 1.3
Electron Affinity 93.91 kJ/mol
Ionization Energy 635 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.

Photograph

Image of Mendelevium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.