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100 Fm Fermium 257

Fermium

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

Fermium is a synthetic element with symbol Fm and atomic number 100. It is a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared.

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Quick Facts

Atomic Number 100
Period 7
Group 14
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 257
Density N/A g/L
Molar Heat N/A J/(mol·K)
Phase Transition (Melting & Boiling Points)

Fermium melts at 1800 K. The boiling point is currently unknown.

Atomic Properties

Electron Config [Rn] 5f12 7s2
Electronegativity 1.3
Electron Affinity 33.96 kJ/mol
Ionization Energy 627 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 Fermium 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.