Astatine Atomic number 85 Island of stability Commentary

Berkeley—Dale R. Corson, Kenneth Ross MacKenzie, Emilio Segrè elements

Astatine

• Dmitri Mendeleev said that an unknown halogen
• should come after iodine, eka-iodine.
• Fred Allison thought he found it
• and called it alabamine.
• Rajendralal De thought he found it
• and called it dakin.
• Horia Hulubei and Yvette Cauchois thought they found it
• and called it dor.
• Walter Minder thought he found it
• and called it helvetium.
• Walter Minder and Alice Leigh-Smith thought they found it
• and called it anglo-helvetium.
• Corson, MacKenzie, and Segrè made their own astatine-211
• bombarding bismuth-209 with alpha particles in a cyclotron.

Atomic number 85

• Astatine was eventually found as a decay product
• in the uranium, actinium, and neptunium decay chains.
• Astatine has at least thirty-nine isotopes
• and none are stable.
• Until Berta Karlik and Traude Bernert
• found naturally occurring actinium,
• people were reluctant to recognize as legitimate
• unstable and synthetic isotopes of astatine.

Island of stability

• Astatine and every heavier element
• spontaneously disintegrate.
• Only seven of the remaining thirty-three elements
• can be found in nature.
• Some think we will eventually make
• an even heavier element that resists decay,
• like finding Amelia Erhart or a daughter of hers
• alive on an island in the Pacific.