Oxygen

DIATOMIC NONMETAL

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

Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal and oxidizing agent that readily forms compounds (notably oxides) with most elements. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.

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Quick Facts

Atomic Number 8

Period 2

Group 16

Phase Gas

Appearance Unknown

About Diatomic Nonmetals

Diatomic nonmetals naturally exist as molecules of two atoms (e.g., O₂, N₂). They are typically gases at room temperature.

History

Discovered By Carl Wilhelm Scheele

Named By Antoine Lavoisier

Physical Properties

Atomic Mass 15.999

Density 1.429 g/L

Molar Heat N/A J/(mol·K)

Phase Transition (Melting & Boiling Points)

Oxygen melts at 54.36 K and boils at 90.188 K.

Atomic Properties

Electron Config [He] 2s2 2p4

Electronegativity 3.44

Electron Affinity 140.976 kJ/mol

Ionization Energy 1313.9 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.

Emission Spectrum Emission spectrum of Oxygen

Photograph

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.