Radioactive decay

• Elements with fewer protons, such as the ones near the top of the periodic table close periodic table A tabular representation of all known elements in order based on atomic number, eg all the noble gases are found on the right of the periodic table, are stable if they have the same number of neutrons and protons For example carbon, carbon-12 is stable and has six protons and six neutrons.
• As the number of protons increases, more neutrons are needed to keep the nucleus stable.
• Nuclei with too many, or too few, neutrons do exist naturally but are unstable and will decay close radioactive decay The process in which unstable atomic nuclei break apart or change, releasing radiation as they do so by emitting radiation close radiation Energy carried by particles from a radioactive substance, or spreading out from a source.