Fermium
ActinideAtomic Number: 100 • Atomic Mass: 257.0000 u • Period: 7 • Group: 102
Atomic Structure
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹²The electron configuration represents the distribution of electrons in atomic orbitals, showing how they are arranged in energy levels and subshells.
Subatomic Particles
100
Positive charge
157
No charge
100
Negative charge
Atomic Number & Mass Number
The atomic number (100) represents the number of protons in the nucleus.
The mass number (257) is the sum of protons and neutrons in the nucleus.
Isotopes
Isotopes are variants of an element that have the same number of protons but different numbers of neutrons.
Fm-255
Fm-257
Stability & Half-Life
Half-Life Information
100.5 days for Fm-257
Half-life is the time required for half of the atoms of a radioactive isotope to decay.
Periodic Table Location
Period: 7
Group: 102
Category: Actinide
The period indicates the main energy level, while the group suggests similar chemical properties.