Radioactivity Some substances spontaneously emit radiation – radioactivity The rays and particles emitted are called “radiation”. Radioactive elements change their identity – they can change into another element They do this because the nuclei are unstable Changes to atom’s nucleus is called a nuclear reaction Something else Dalton got wrong.

Radioactive Decay Radioactive elements emit energy as radiation This is called ‘radioactive decay’ Unstable atoms undergo radioactive decay until they form stable atoms

Types of Radiation Alpha Radiation – emitting a positively charged particle - α Beta Radiation – emitting a negatively charged particle - β Gamma Radiation – High energy radiation with no mass - γ

α Alpha Radiation Alpha radiation Made up of Alpha particles Alpha particles have 2 protons, 2 neutrons Alpha particles have a 2+ charge α

+ Nuclear Equations Nuclear Equations transmutation - an element is transformed into a new element. This can occur by natural or artificial means. loss of an a particle radium is emitting an a particle                                                      +

Beta Radiation Beta Radiation is fast moving electrons Attracted to positive charged items Charge is 1-

Gamma Radiation High Energy radiation with no mass No charge Usually accompany alpha and beta radiation Account for most of the energy lost during radioactive decay

Review Classify each as a chemical reaction, nuclear reaction, or neither Thorium emits a beta particle: Nuclear Two atoms share electrons to form a bond: Chemical A sample of pure sulfur emits heat as it slowly cools: Neither A piece of iron rusts: chemical