Molybdène (Mo): Bohr Model, Protons, Neutrons & Electrons
Molybdène is element number 42, a transition metal in group 6, period 5. Its atom has 42 protons, 56 neutrons and 42 electrons arranged in 5 shells: 2, 8, 18, 13, 1.
- 42 protons
- 56 neutrons
- 42 electrons
Protons, neutrons and electrons in molybdenum
Le atomic number of molybdenum is 42, so every molybdenum atom has 42 protons. A neutral atom has the same number of electrons, 42. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For molybdenum-98, that is 98 − 42 = 56 neutrons. Molybdenum has 7 stable isotopes, with 50, 52, 53, 54, 55, 56, 58 neutrons.
How to draw the Bohr model of molybdenum
- Draw the nucleus and write 42 p⁺ et 56 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 18 electrons on it.
- Draw the fourth shell and put 13 electrons on it.
- Draw the fifth shell and put 1 electron on it.
- Check: 2 + 8 + 18 + 13 + 1 = 42 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, 18, 13, 1) is the one to draw.
Electron configuration
The electron configuration of molybdenum is [Kr] 5s¹ 4d⁵. As a transition metal it fills an inner d-subshell, and its common ion is Mo³⁺.
Key facts about molybdenum
| Symbol | Mo |
|---|---|
| Atomic number | 42 |
| Relative atomic mass | 95.95 |
| Group · period · block | group 6 · period 5 · d-block |
| Type | Métal de transition |
| State at 25 °C | solid |
| Couches électroniques | 2, 8, 18, 13, 1 |
| Electron configuration | [Kr] 5s¹ 4d⁵ |
| Électrons de valence | varies (outer shell: 1) |
| Common ion | Mo³⁺ |
| Electronegativity (Pauling) | 2.16 |
| First ionisation energy | 7.09 eV (684 kJ/mol) |
| Atomic radius (empirical) | 145 pm |
Où molybdenum sits on the periodic table
Foire aux questions
How many protons, neutrons and electrons does molybdenum have?
Molybdenum has 42 protons and 42 electrons (atomic number 42). Its most common isotope, molybdenum-98, has 98 − 42 = 56 neutrons.
What is the electron configuration of molybdenum?
[Kr] 5s¹ 4d⁵. In shells that is 2, 8, 18, 13, 1.
How many valence electrons does molybdenum have?
Molybdenum is a transition metal, so its valence electrons are spread over two shells; its outermost shell holds 1.
Where is molybdenum on the periodic table?
In group 6, period 5, in the d-block. It is a transition metal.
