radium [Ra]
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Introduction
From the Latin radius, ray. Discovered in 1898 by Marie Curie & Pierre Curie in Pitchblende.
Occurrence
- occurs naturally in a uranium & thorium minerals
- occurs in combination in minute quantities in minerals (as pitchblende or carnotite)
Characteristics
- intensely radioactive shining white metallic metallic
- blackens on exposure to air
- resembles barium chemically
- reactive with oxygen
- decomposes in air
- the surface of radium is covered with a protective thin layer of the oxide
- radium emits alpha particles & gamma rays to form radon
- luminescence
Uses
- radiation therapy
- luminous materials
- once used in the mid 1900s as a luminous paint to make the hands & numbers on watches & clocks glow in the dark