Beta and Positron Radiation

Model of the atom - Recap

Protons and neutrons are known as NUCLEONS Properties of sub-atomic particles Relative Charge Relative Mass Protons and neutrons are known as NUCLEONS

Representing Atoms Number of protons and neutrons (or nucleons) Number of protons only

Nuclear Radiation The nucleus of some unstable atoms (radioisotopes) emit nuclear radiation. Alpha, beta and gamma are types of nuclear radiation that can be emitted. gamma beta alpha

Beta Decay There are two types of beta particles:- beta minus (electron) and beta plus (positron) -1 - +1 + Positron Electron

Beta radiation properties The ß- radiation consists of a stream of high-energy electrons. They are ionising and can penetrate paper and thin sheets of aluminium but are stopped by thin sheets of other metals.

The positron is an antiparticle of the electron, it has the same mass but opposite charge Relative Charge Relative Mass

Beta minus (-) decay

(-) + -1 N 14 7 C 6 -

Cs Ba -  + Beta minus decay e.g. 2 Caesium 137 (137Cs) undergoes beta negative (β-) decay: + Cs 55 137 Ba 56  electron -1 -

Beta plus (+) decay (higher) Sodium 22 (22Na) undergoes beta positive (β+) decay: +1 + + Na 11 22 Ne 10  positron In beta positive (β+) decay a proton becomes a neutron.

Summary Questions