26 - Iron transition metal
Discovered in ~5000 BC
Iron is a chemical element with symbol Fe (from Latin:ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core.
Periodic table
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 14 | 2 in 3s + 6 in 3p + 6 in 3d |
| 4 | 2 | 2 in 4s |
Electron shells
lustrous metallic with a grayish tinge Appearance
55.8 u Atomic Mass
1.4 Å Atomic Radius
3.13k K Boiling Point
8 Group
2, 3 Common Oxidation States
1.32 Å Covalent Radius
7.87 g/cm³ Density
14.8 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d6 Electron Configuration
[Ar] 3d6 4s2 Electron Configuration (semantic)
1.83 Electronegativity
26 Electrons
7.9 eV First Ionization Energy
2, 3 ICSD Oxidation States
762.5, 1561.9, 2957, 5290, 7240, 9560, 12060, 14580, 22540, 25290, 28000, 31920, 34830, 37840, 44100, 47206, 122200, 131000, 140500, 152600, 163000, 173600, 188100, 195200, 851800, 895161 kJ/mol Ionization Energies
1.81k K Melting Point
61 Mendeleev Number
25.1 J/(mol·K) Molar Heat
4 Number of Shells
30 Neutrons
26 Atomic Number
10 Number of Isotopes
-2, -1, 1, 2, 3, 4, 5, 6 Oxidation States
4 Period
Solid Phase
26 Protons
2, 8, 14, 2 Electron Shell Occupations