What is Thallium?

Thallium, the eighty-first element on the periodic table, is a soft, bluish-gray post-transition metal. It's sneaky, toxic, and quietly useful.

Atomic Number: 81

Symbol: Tl

Atomic Mass: 204.38 u

Category: Post-Transition Metal

State at Room Temperature: Solid

Discovered By: William Crookes (1861)

⚛️ Atomic Structure of Thallium

Thallium has eighty-one protons, one hundred twenty-three neutrons (in its most common isotope, Thallium-205), and eighty-one electrons, with three in its outer shell.

  • 🟢 Protons: 81
  • 🔴 Neutrons: 123 (Most common isotope, Thallium-205)
  • 🟡 Electrons: 81

💡 Did you know? Thallium glows green under a spectroscope!

🔬 Thallium Properties

Thallium is soft, malleable, and dense. It melts at 304°C (579°F), tarnishes in air, and is highly toxic to living organisms.

🧪 How Was Thallium Discovered?

In 1861, English chemist William Crookes identified Thallium via its green spectral line in a zinc ore sample, naming it from the Greek "thallos" (green shoot).

⚡ Uses of Thallium

  • 💻 Electronics: Infrared detectors.
  • 🩺 Medicine: Heart stress tests.
  • 🔬 Glass: High-index lenses.
  • ☠️ Past: Rat poison (now banned).

💡 Fun Facts About Thallium

  • 🌿 Green spectral glow.
  • ☠️ Infamous poison.
  • 🔍 Rare in nature.
  • 🩺 Scans hearts.

⚠️ Safety & Precautions

Thallium is highly toxic. Avoid all contact, inhalation, or ingestion; use protective gear, ventilate areas, and store securely under strict regulations.

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