RADIOACTIVE DECAY RADIOACTIVE DECAY Yesterday we learned that

RADIOACTIVE DECAY Yesterday we learned that all elements have different isotopes. Example: 1 H

RADIOACTIVE DECAY An unstable isotope is said to be radioactive. Radioactive (unstable) isotopes =

RADIOACTIVE DECAY Carbon-12 and carbon-13 are stable, but carbon-14 is radioactive. 6 p+ and

WHAT MAKES A RADIOISOTOPE UNSTABLE? An isotope can be unstable if: it is too

TYPES OF RADIATION Alpha radiation Composition: Alpha particle (helium nucleus) Symbol: or 4 He

TYPES OF RADIATION Beta radiation Composition: Beta particle (electron) Symbol: or e Charge: -1

TYPES OF RADIATION Gamma radiation Composition: High-energy EM radiation Symbol: Charge: 0 Mass: 0

USES OF RADIATION Radioisotopic labelling – can be used to track the movement of

Slides: 12

Download presentation

RADIOACTIVE DECAY

RADIOACTIVE DECAY Yesterday we learned that all elements have different isotopes. Example: 1 H (1 proton, 0 neutrons) 2 H (1 proton, 1 neutron) 3 H (1 proton, 2 neutrons) Some isotopes are stable and will last essentially forever. Some aren’t stable.

RADIOACTIVE DECAY An unstable isotope is said to be radioactive. Radioactive (unstable) isotopes = radioisotopes Radioisotopes eventually decay into more stable forms. A radioisotope releases energy by emitting radiation during the process of radioactive decay.

RADIOACTIVE DECAY Carbon-12 and carbon-13 are stable, but carbon-14 is radioactive. 6 p+ and 6 n 0 6 p+ and 7 n 0 6 p+ and 8 n 0

WHAT MAKES A RADIOISOTOPE UNSTABLE? An isotope can be unstable if: it is too heavy (more than 83 protons). its n 0 to p+ ratio is too high. its n 0 to p+ ratio is too low.

TYPES OF RADIATION Alpha radiation Composition: Alpha particle (helium nucleus) Symbol: or 4 He Charge: +2 Mass: 4 amu Penetrating power: Low (0. 05 mm body tissue) Shielding: Paper, clothing Effect on nucleus: Z – 2, A – 4

ALPHA DECAY alpha

TYPES OF RADIATION Beta radiation Composition: Beta particle (electron) Symbol: or e Charge: -1 Mass: 1/1837 amu Penetrating Power: Moderate (4 mm body tissue) Shielding: Metal foil Effect on nucleus: Z + 1; A unchanged.

BETA DECAY e-

TYPES OF RADIATION Gamma radiation Composition: High-energy EM radiation Symbol: Charge: 0 Mass: 0 Penetrating power: Very high Shielding: Lead, concrete Effect on nucleus: decreases energy

USES OF RADIATION Radioisotopic labelling – can be used to track the movement of a particular substance through a living organism. Radiometric dating – used to determine the age of ancient objects. Many uses in medicine, from imaging to cancer therapy.