Einsteinium (Es): Bohr Model, Protons, Neutrons & Electrons
Einsteinium is element number 99, an actinide in the f-block (the actinide row drawn below the table), period 7. Its atom has 99 protons, 153 neutrons and 99 electrons arranged in 7 shells: 2, 8, 18, 32, 29, 8, 2.
- 99 protons
- 153 neutrons
- 99 electrons
Protons, neutrons and electrons in einsteinium
Le atomic number of einsteinium is 99, so every einsteinium atom has 99 protons. A neutral atom has the same number of electrons, 99. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For einsteinium-252, that is 252 − 99 = 153 neutrons. Every isotope of einsteinium is radioactive; 252 is the mass number of its most stable one.
How to draw the Bohr model of einsteinium
- Draw the nucleus and write 99 p⁺ et 153 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 29 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 + 29 + 8 + 2 = 99 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, 29, 8, 2) is the one to draw.
Electron configuration
The electron configuration of einsteinium is [Rn] 7s² 5f¹¹. As an actinide it fills an inner f-subshell, and its common ion is Es³⁺.
Key facts about einsteinium
| Symbol | Es |
|---|---|
| Atomic number | 99 |
| Relative atomic mass | [252] |
| Group · period · block | f-block · period 7 |
| Type | Actinide |
| State at 25 °C | solid |
| Couches électroniques | 2, 8, 18, 32, 29, 8, 2 |
| Electron configuration | [Rn] 7s² 5f¹¹ |
| Électrons de valence | varies (outer shell: 2) |
| Common ion | Es³⁺ |
| Electronegativity (Pauling) | 1.30 |
| First ionisation energy | 6.42 eV (619 kJ/mol) |
| Atomic radius (empirical) | — |
Où einsteinium sits on the periodic table
Foire aux questions
How many protons, neutrons and electrons does einsteinium have?
Einsteinium has 99 protons and 99 electrons (atomic number 99). Its most common isotope, einsteinium-252, has 252 − 99 = 153 neutrons.
What is the electron configuration of einsteinium?
[Rn] 7s² 5f¹¹. In shells that is 2, 8, 18, 32, 29, 8, 2.
How many valence electrons does einsteinium have?
Einsteinium is an actinide, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is einsteinium 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.
