It takes energy to hold the protons and neutrons together in the nucleus. There are several different forms of ionising radiation. Alpha and beta radiation are tiny atomic particles travelling at high speeds. Radiation can cause damage to living things, like the cells in our body, but this can also be a good thing. For example, radiotherapy treatment for cancer works by using radiation to destroy the cancer cells.
Radiation occurs naturally.
We are surrounded by radiation. Radioactivity was discovered by Henri Becquerel in 1896, the year after Wilhelm Rontgen discovered X-rays. There are now nine known naturally occurring radioactive elements. Nuclear fission is the splitting of the nucleus of a radioactive element into two smaller fragments. The nucleus is caused to fission by striking it with a neutron.