Thallium (Tl)

Thallium is a soft, gray post-transition metal that is not found free in nature.

Core Principles & Analysis

• William Crookes discovered thallium spectroscopically in 1861 by its bright green line, naming it from the Greek for a green shoot.
• Its colorless, nearly tasteless toxic salts earned it the nickname 'the poisoner's poison' before sales were restricted.
• Thallium-201 is used in cardiac stress-test imaging, and thallium compounds appear in infrared optics and low-temperature thermometers.

Specifications & Metrics

• NUM: 81
• SYMBOL: Tl
• CATEGORY: Post-transition Metal