Mercury (Hg): Bohr Model, Protons, Neutrons & Electrons
Mercury is element number 80, a transition metal in group 12, period 6. Its atom has 80 protons, 122 neutrons and 80 electrons arranged in 6 shells: 2, 8, 18, 32, 18, 2.
Protons, neutrons and electrons in mercury
The atomic number of mercury is 80, so every mercury atom has 80 protons. A neutral atom has the same number of electrons, 80. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For mercury-202, that is 202 − 80 = 122 neutrons. Mercury has 7 stable isotopes, with 116, 118, 119, 120, 121, 122, 124 neutrons.
How to draw the Bohr model of mercury
- Draw the nucleus and write 80 p⁺ and 122 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 18 electrons on it.
- Draw the sixth shell and put 2 electrons on it.
- Check: 2 + 8 + 18 + 32 + 18 + 2 = 80 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, 18, 2) is the one to draw.
Electron configuration
The electron configuration of mercury is [Xe] 6s² 4f¹⁴ 5d¹⁰. As a transition metal it fills an inner d-subshell, and its common ion is Hg²⁺.
Key facts about mercury
| Symbol | Hg |
|---|---|
| Atomic number | 80 |
| Relative atomic mass | 200.59 |
| Group · period · block | group 12 · period 6 · d-block |
| Type | Transition Metal |
| State at 25 °C | liquid |
| Electron shells | 2, 8, 18, 32, 18, 2 |
| Electron configuration | [Xe] 6s² 4f¹⁴ 5d¹⁰ |
| Valence electrons | varies (outer shell: 2) |
| Common ion | Hg²⁺ |
| Electronegativity (Pauling) | 2.00 |
| First ionisation energy | 10.44 eV (1007 kJ/mol) |
| Atomic radius (empirical) | 150 pm |
Where mercury sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does mercury have?
Mercury has 80 protons and 80 electrons (atomic number 80). Its most common isotope, mercury-202, has 202 − 80 = 122 neutrons.
What is the electron configuration of mercury?
[Xe] 6s² 4f¹⁴ 5d¹⁰. In shells that is 2, 8, 18, 32, 18, 2.
How many valence electrons does mercury have?
Mercury is a transition metal, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is mercury on the periodic table?
In group 12, period 6, in the d-block. It is a transition metal.
