About Thallium
- It is globally known as the ‘poisoner’s poison’.
- It was discovered by Sir William Crookes in 1861.
- It is a metal belonging to the main Group 13 (IIIa, or boron group) of the periodic table.
- It was used historically as a rodenticide.
- Properties
- It is tasteless and odorless.
- It is a soft, heavy and low-melting element of low tensile strength.
- It does not dissolve in water.
- It dissolves slowly in hydrochloric acid and dilute sulfuric acid and rapidly in nitric acid.
- It is found in trace amounts in the earth’s crust.
- This metal continues to oxidize upon prolonged contact with air, generating a heavy nonprotective oxide crust.
- Trace amounts of thallium are present in sulfide ores of zinc and lead; in the roasting of these ores, the thallium becomes concentrated in the flue dusts, from which it is recovered.
- Applications: It is used in the manufacture of electronics, low temperature thermometers, optical lenses, and imitation precious jewels.
Q1) What is a periodic table?
It is a tabular arrangement of chemical elements, organized by their atomic number, electron configuration, and recurring chemical properties. Elements in the periodic table are ordered in rows (periods) and columns (groups).
Source: Scientist kills husband, in-laws: What is Thallium and why murderers use this poison?
Last updated on February, 2026
→ UPSC Notification 2026 is now out on the official website at upsconline.nic.in.
→ UPSC IFoS Notification 2026 is now out on the official website at upsconline.nic.in.
→ UPSC Calendar 2026 has been released.
→ Check out the latest UPSC Syllabus 2026 here.
→ Join Vajiram & Ravi’s Interview Guidance Programme for expert help to crack your final UPSC stage.
→ UPSC Mains Result 2025 is now out.
→ UPSC Prelims 2026 will be conducted on 24th May, 2026 & UPSC Mains 2026 will be conducted on 21st August 2026.
→ The UPSC Selection Process is of 3 stages-Prelims, Mains and Interview.
→ Prepare effectively with Vajiram & Ravi’s UPSC Prelims Test Series 2026 featuring full-length mock tests, detailed solutions, and performance analysis.
→ Enroll in Vajiram & Ravi’s UPSC Mains Test Series 2026 for structured answer writing practice, expert evaluation, and exam-oriented feedback.
→ Join Vajiram & Ravi’s Best UPSC Mentorship Program for personalized guidance, strategy planning, and one-to-one support from experienced mentors.
→ UPSC Result 2024 is released with latest UPSC Marksheet 2024. Check Now!
→ UPSC Toppers List 2024 is released now. Shakti Dubey is UPSC AIR 1 2024 Topper.
→ Also check Best UPSC Coaching in India







