The Atomic Nucleus and Radioactivity
Inside the tiny core of every atom, and the invisible rays it can shoot out
Big Idea: Almost all the mass of an atom is packed into a nucleus about 100 000 times smaller than the atom itself. That nucleus is built from protons and neutrons. Some nuclei are unstable and spontaneously throw out alpha, beta or gamma rays — this is radioactivity. Understanding it explains everything from medical scans to the heat inside the Earth.
By the end you will be able to:
- describe the nucleus using the charge number Z and the mass number A,
- explain what isotopes are and read nuclide symbols like 23892U,
- compare the nature, charge, mass and penetrating power of alpha, beta and gamma rays,
- write and balance simple decay equations,
- use the idea of half-life to work out how much of a sample is left.