Thallium | Chemistry

Chemical Education Digital Library, Madison, Wisconsin, U.S.A.

Thallium, 81, Chemical Education Library, Wisconsin USA

Thallium: Thallium means “green twig.” William Crookes chose the name after he discovered its beautiful green emission spectrum — the color of new spring leaves. Thallium’s dark side is toxicity. Once sold as a rat and insect poison, this deadliest of the elements has a long history of poisoning humans. The ghostly letters PTL! on the left refer to Periodic Table Live!, a free, interactive periodic table from the Chemical Education Digital Library, where you can learn more about thallium and all the other elements.

Original artwork by Katrin Sticha, Graphic Art student, Mount Mary College. Spectrum photo: James Maynard, Chemical Demonstrator, University of Wisconsin-Madison. Organized by Lynn Diener, Chemical Education Digital Library, Madison, Wisconsin, U.S.A.

Atomic properties*

Name:

Thallium

Symbol:

Tl

Atomic number:

81

Atomic mass:

204.38 amu

Melting point:

304°C

Boiling point:

1473°C

Density:

11.8 g/cm³

Electronegativity:

1.8

# of Isotopes:

3

State:

Solid

Colour:

Silvery-white**

Classification:

Metallic**

* Haynes, W. M. (2011). CRC Handbook of Chemistry and Physics, 91st edition: http://www.hbcponline.com/ Retrieved April 7, 2011

** Winter, M. (2010). Home of the Periodic Table. Retrieved April 8, 2011, from Web Elements: http://www.webelements.com/