Carl Wilhelm Scheele, a relentless chemist of the 18th century, discovered Oxygen in 1771—a gas that would prove essential not just for respiration, but for the fiery dance of combustion, corrosion, and the symphony of planetary chemistry. Today, it forms about 20.95% of Earth’s atmosphere, and nearly half of the Earth’s crust as oxides, subtly omnipresent but rarely visible.

🧪 Atomic Details

• Symbol: O
• Atomic Number: 8
• Group: Other Nonmetal
• Block: p-block
• Atomic Mass: 15.999 u
• Electronegativity: 3.44
• Phase at STP: Gas (Colorless; pale blue as solid or liquid)
• Paramagnetic by nature

The electron configuration, 2s² 2p⁴, sets the stage for its reactive character—it pulls electrons like a magnet and often settles into the O²⁻ ion.

🔥 Physical Chemistry

• Melting Point: −218.79 °C
• Boiling Point: −182.96 °C
• Density: 0.001429 g/cm³
• Specific Heat Capacity: 0.918 J/(g·K)

This stark range in sonic speeds hints at how tightly packed molecules are in each state—ethereal in air, viscous in chill.

🌍 Oxygen Through the Universe

After hydrogen and helium, Oxygen reigns as the third most abundant element in the universe by mass—a heavyweight in cosmic chemistry.

🧊 Crystal Structure

It adopts a cubic crystal structure, with lattice constants:

• a = 5.403 Å
• b = 3.429 Å
• c = 5.086 Å

Debye Temperatures:

• Low temperature limit: 155 K
• Room temperature: 140 K

Isotopes

Oxygen has 16 known isotopes, ranging from the fleeting O-11 to the stable, foundational O-16, O-17, and O-18.
The radioactive variants exhibit decays via β⁺, β⁻, and even 2-proton or 2-neutron modes—a complex ballet of subatomic instability.

🔗 Dive Deeper

Want even more Oxygen intel? Get Atomic – Periodic Table now:

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