Unstable atoms will attempt to become stable by changing into a new isotope or element, and energy is released in the form of ionizing radiation until the forces in the nucleus are balanced and stable. The series of changes that a given radioactive element undergoes is called a decay chain.

The unstable nucleus of radioactive atoms emit radiation. When this occurs, a new atom and element are formed. This process is called radioactive decay. It continues until the forces in the unstable nucleus are balanced.

An atom can be considered unstable in one of two ways. If it picks up or loses an electron, it becomes electrically charged and highly reactive. Such electrically charged atoms are known as ions. Instability can also occur in the nucleus when the number of protons and neutrons is unbalanced.

This decay, called spontaneous fission, happens when a large unstable nucleus spontaneously splits into two (or occasionally three) smaller daughter nuclei, and generally leads to the emission of gamma rays, neutrons, or other particles from those products.

In unstable nuclei the strong nuclear forces do not generate enough binding energy to hold the nucleus together permanently. Too many neutrons or protons upset this balance disrupting the binding energy from the strong nuclear forces making the nucleus unstable. …

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Answer Expert Verified Answer is: decay constant for uranium-238 is 1,54·10⁻¹⁰ 1/y. The half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration. t1/2 = 4.5·10⁹ y. λ = 0,693 ÷ t1/2.

Nuclear decay occurs when the nucleus of an atom is unstable and spontaneously emits energy in the form of radiation. The result is that the nucleus changes into the nucleus of one or more other elements. These daughter nuclei have a lower mass and are more stable (lower in energy) than the parent nucleus.