Osmium (Os)
Osmium is element 76, a transition metal in group 8, period 6. A neutral atom has 76 protons, 114 neutrons and 76 electrons, 2 of them valence electrons.
Transition metal- Atomic number
- 76
- Atomic mass
- 190.2 u
- Valence electrons
- 2*
- Protons · neutrons
- 76 · 114
- Electrons per shell
- 2, 8, 18, 32, 14, 2
- At room temperature
- solid
Bohr model of osmium
The Bohr model draws osmium as a nucleus of 76 protons and 114 neutrons, with its 76 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 14 in shell 5, 2 in shell 6. Press Build the atom to watch the shells fill from the inside out. The outer ring (the P shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of osmium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁶
Short form (noble gas notation): [Xe] 6s² 4f¹⁴ 5d⁶. The [Xe] stands for the electrons of xenon, the noble gas before it.
How many valence electrons does osmium have?
Osmium has 2 valence electrons.
Osmium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 6), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 76 | equal to the atomic number |
|---|---|---|
| Electrons | 76 | equal to the protons in a neutral atom |
| Neutrons | 114 | mass number 190 − 76 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Osmium properties
| Symbol | Os |
|---|---|
| Category | Transition metal |
| Group · period · block | 8 · 6 · d |
| Atomic mass | 190.2 u |
| State at 25 °C | solid |
| Melting point | 3,306 K (3,030 °C, 5,490 °F) |
| Boiling point | 5,285 K (5,010 °C, 9,050 °F) |
| Density | 22.57 g/cm³ |
| Electronegativity (Pauling) | 2.2 |
| Atomic radius | 216 pm |
| First ionization energy | 8.7 eV |
| Electron affinity | 1.1 eV |
| Oxidation states | +4, +3 |
| Common ion charge | +4, +3 |
| Discovered | 1803 by Smithson Tennant |
Where osmium sits on the periodic table
Group 8: Iron, Ruthenium, Hassium.
Questions about osmium
How many valence electrons does osmium have?
Osmium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does osmium have?
A neutral osmium atom has 76 protons and 76 electrons. Its most common form has about 114 neutrons (mass number 190 − 76 protons).
What is the electron configuration of osmium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁶, written in short form as [Xe] 6s² 4f¹⁴ 5d⁶.
What does the Bohr model of osmium look like?
A nucleus of 76 protons and 114 neutrons, circled by 6 electron shells holding 2, 8, 18, 32, 14, 2 electrons.
What is the atomic number of osmium?
76. The atomic number is the number of protons in the nucleus, and it is what makes an atom osmium.