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76 Os Osmium 190.233

Osmium

TRANSITION METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

Osmium (from Greek osme (ὀσμή) meaning "smell") is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3.

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Quick Facts

Atomic Number 76
Period 6
Group 8
Phase Solid
Appearance silvery, blue cast
About Transition Metals

Transition metals are elements with partially filled d-orbitals. They are hard, have high melting points, and often form colored compounds.

History

Discovered By Smithson Tennant
Named By Unknown

Physical Properties

Atomic Mass 190.233
Density 22.59 g/L
Molar Heat 24.7 J/(mol·K)
Phase Transition (Melting & Boiling Points)

Osmium melts at 3306 K and boils at 5285 K.

Atomic Properties

Electron Config [Xe] 4f14 5d6 6s2
Electronegativity 2.2
Electron Affinity 103.99 kJ/mol
Ionization Energy 840 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.

Photograph

Image of Osmium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.