There is a 50 percent chance that one of the unstable atoms will decay within an hour.

As the uranium reacts its radioactivity produces unstable atoms.

For example, an electron may combine with a positron to form a positronium, an unstable atom.

Alpha particles, protons, and X-rays are emitted during the radioactive decay of unstable atoms.

A sample of the substance is synthesized with a high concentration of unstable atoms.

"Each unstable atom that explodes will do so with nuclear energy," said Hunter.

"If their unstable atoms still exist in any form, the danger of nuclear explosion remains in effect."

These high energy particles or electromagnetic radiation are emitted by unstable atoms as they go through transition to a more stable state.

Because many of these elements have unstable atoms, various other elements are made by their radioactive decay.

In each component robot, the first explosion will set off the other unstable atoms.