In 1913, an element was known to "emanate" from radium-226 by $\alpha$ emission and then to decay to polonium-218, also by $\alpha$ emission. What was the unknown element?

Question

Quizplus · Accepted Answer

The given information describes a decay chain starting with radium-226 and ending with polonium-218. The alpha decay notation (F1F1F1S1F1F1F10) indicates that an alpha particle (helium nucleus) is emitted from the nucleus. The unknown element must have an atomic number 2 less than radium-226 (since an alpha particle has an atomic number of 2). This means the unknown element has an atomic number of 88 (226-2=224), which corresponds to the element radon (Rn). Therefore, the answer is choice A.

In 1913, an Element Was Known to "Emanate" from Radium-226 α\alphaα

In 1913, an Element Was Known to "Emanate" from Radium-226 $\alpha$