---
title: "Osmium (Os): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/osmium.html
description: "Osmium (Os), element 76: atomic mass 190.23, electron configuration [Xe] 4f¹⁴ 5d⁶ 6s², group 8, period 6, d-block transition metal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
76Os190.23

# Osmium (Os) – element 76

Osmium is a chemical element with the symbol **Os** and atomic number **76**. It is a transition metal in group 8, period 6 of the periodic table (d-block), and is a solid at room temperature.

Osmium (Os) has atomic number 76, atomic mass 190.23 u and electron configuration [Xe] 4f14 5d6 6s2.

[Download periodic table PDF](https://www.moldraw.com/printables/periodic-table.pdf)[Open interactive periodic table](https://www.moldraw.com/tools/free-chem-tools/interactive-periodic-table.html)

## Osmium facts

| Symbol | Os |
| --- | --- |
| Atomic number | 76 |
| Atomic mass | 190.23 u (g/mol) |
| Category | transition metal |
| Group | group 8 |
| Period | 6 |
| Block | d-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d6 |
| Noble-gas notation | [Xe] 4f14 5d6 6s2 |
| Electrons per shell | 2, 8, 18, 32, 14, 2 |

## Bohr model and shells

Osmium has 76 electrons in 6 shells: 2, 8, 18, 32, 14, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the [electron configuration calculator](https://www.moldraw.com/tools/free-chem-tools/electron-configuration-calculator.html).

## Physical and atomic properties

| Melting point | 3306 K (3032.8 °C) |
| --- | --- |
| Boiling point | 5285 K (5011.9 °C) |
| Density | 22.59 g/cm³ |
| Electronegativity (Pauling) | 2.2 |
| Electron affinity | 103.99 kJ/mol |
| Ionization energies | 840, 1600 kJ/mol (1st, 2nd) |
| Molar heat capacity | 24.7 J/(mol·K) |
| Discovered by | Smithson Tennant |

Use the atomic mass in the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html) for any formula containing Os.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of osmium?

The atomic mass of osmium is 190.23 u, so one mole of osmium atoms weighs 190.23 g.

### What is the electron configuration of osmium?

Osmium has 76 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁶, or [Xe] 4f¹⁴ 5d⁶ 6s² in noble-gas notation. Electrons per shell: 2, 8, 18, 32, 14, 2.

### Is osmium a metal?

Yes. Osmium is a transition metal.

### Where is osmium on the periodic table?

Osmium is in group 8, period 6, in the d-block.

Data: [Periodic-Table-JSON](https://github.com/Bowserinator/Periodic-Table-JSON) (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.