Mendeleevium (Md): Bohr Model, Protons, Neutrons & Electrons
Mendeleevium is element number 101, an actinide in the f-block (the actinide row drawn below the table), period 7. Its atom has 101 protons, 157 neutrons and 101 electrons arranged in 7 shells: 2, 8, 18, 32, 31, 8, 2.
- 101 protons
- 157 neutrons
- 101 electrons
Protons, neutrons and electrons in mendelevium
Le atomic number of mendelevium is 101, so every mendelevium atom has 101 protons. A neutral atom has the same number of electrons, 101. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For mendelevium-258, that is 258 − 101 = 157 neutrons. Every isotope of mendelevium is radioactive; 258 is the mass number of its most stable one.
How to draw the Bohr model of mendelevium
- Draw the nucleus and write 101 p⁺ et 157 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 32 electrons on it.
- Draw the fifth shell and put 31 electrons on it.
- Draw the sixth shell and put 8 electrons on it.
- Draw the seventh shell and put 2 electrons on it.
- Check: 2 + 8 + 18 + 32 + 31 + 8 + 2 = 101 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, 32, 31, 8, 2) is the one to draw.
Electron configuration
The electron configuration of mendelevium is [Rn] 7s² 5f¹³. As an actinide it fills an inner f-subshell, and its common ion is variable.
Key facts about mendelevium
| Symbol | Md |
|---|---|
| Atomic number | 101 |
| Relative atomic mass | [258] |
| Group · period · block | f-block · period 7 |
| Type | Actinide |
| State at 25 °C | unknown |
| Couches électroniques | 2, 8, 18, 32, 31, 8, 2 |
| Electron configuration | [Rn] 7s² 5f¹³ |
| Électrons de valence | varies (outer shell: 2) |
| Common ion | — |
| Electronegativity (Pauling) | 1.30 |
| First ionisation energy | 6.58 eV (635 kJ/mol) |
| Atomic radius (empirical) | — |
Où mendelevium sits on the periodic table
Foire aux questions
How many protons, neutrons and electrons does mendelevium have?
Mendelevium has 101 protons and 101 electrons (atomic number 101). Its most common isotope, mendelevium-258, has 258 − 101 = 157 neutrons.
What is the electron configuration of mendelevium?
[Rn] 7s² 5f¹³. In shells that is 2, 8, 18, 32, 31, 8, 2.
How many valence electrons does mendelevium have?
Mendelevium is an actinide, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is mendelevium on the periodic table?
In the f-block (the actinide row drawn below the table), period 7, in the f-block. It is an actinide.
