Fer (Fe): Bohr Model, Protons, Neutrons & Electrons
Fer is element number 26, a transition metal in group 8, period 4. Its atom has 26 protons, 30 neutrons and 26 electrons arranged in 4 shells: 2, 8, 14, 2.
Protons, neutrons and electrons in iron
Le atomic number of iron is 26, so every iron atom has 26 protons. A neutral atom has the same number of electrons, 26. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For iron-56, that is 56 − 26 = 30 neutrons. Iron has 4 stable isotopes, with 28, 30, 31, 32 neutrons.
How to draw the Bohr model of iron
- Draw the nucleus and write 26 p⁺ et 30 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 14 electrons on it.
- Draw the fourth shell and put 2 electrons on it.
- Check: 2 + 8 + 14 + 2 = 26 electrons, the same as the number of protons.
From potassium onwards the shells don’t simply fill as 2, 8, 8: the fourth shell starts before the third is full, so the real arrangement above (2, 8, 14, 2) is the one to draw.
Electron configuration
The electron configuration of iron is [Ar] 4s² 3d⁶. As a transition metal it fills an inner d-subshell, and its common ion is Fe²⁺.
Key facts about iron
| Symbol | Fe |
|---|---|
| Atomic number | 26 |
| Relative atomic mass | 55.845 |
| Group · period · block | group 8 · period 4 · d-block |
| Type | Métal de transition |
| State at 25 °C | solid |
| Couches électroniques | 2, 8, 14, 2 |
| Electron configuration | [Ar] 4s² 3d⁶ |
| Électrons de valence | varies (outer shell: 2) |
| Common ion | Fe²⁺ |
| Electronegativity (Pauling) | 1.83 |
| First ionisation energy | 7.90 eV (762 kJ/mol) |
| Atomic radius (empirical) | 140 pm |
Où iron sits on the periodic table
Foire aux questions
How many protons, neutrons and electrons does iron have?
Iron has 26 protons and 26 electrons (atomic number 26). Its most common isotope, iron-56, has 56 − 26 = 30 neutrons.
What is the electron configuration of iron?
[Ar] 4s² 3d⁶. In shells that is 2, 8, 14, 2.
How many valence electrons does iron have?
Iron is a transition metal, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is iron on the periodic table?
In group 8, period 4, in the d-block. It is a transition metal.
