Introduction to Isotopes, Radioactivity, and Radioactive decay

Isotopes

Atoms of the same element with the same number of protons (atomic number) but different number of neutrons (different atomic mass)

What is the kinetic isotope effect?

The change in the rate of a chemical reaction when an atom in the reactants is replaced by one of its isotopes.

What are the uses of the kinetic isotope effect?

• Determining which bonds are broken in the RDS

• Studying enzyme catalysed reactions

• Investigating reaction transition states and bond strength differences

Name the three types of radiation

Alpha, beta, gamma

The decay of unstable atomic nuclei:

What is the exponential decay law?

What is the Activity-time relationship?

What is the link between activity and number of nuclei?

What’s the half life equation for nuclei?

1 bq =

1 bq = 1 disintegration per second

1 Ci =

1 Ci = 3.7 × 10¹⁰ Bq

¹⁸F decays to ¹⁸O, with a half life of 109.7 minutes. What is the decay constant for ¹⁸F?

Remember to convert units if it has to be in seconds or something.

What’s the relationship between the decay constant and the half life?

• The decay constant (λ) and the half-life (t₁/₂) are inversely related.

• When one increases, the other decreases.

What is radiolabelling?

A technique in which a radioactive isotope is incorporated into a molecule so that the molecule can be tracked or detected by measuring the radiation it emits.