The Discovery of Radioactivity

GROUP 8Richard LoewJace GrandinettiEdward DuranEmil Blumburg

TopicsDiscovery of RadioactivityProperties of Radioactive atomsImpact on PhysicsFuture Applications

• Becquerel discovered radioactivity while studying phosphorescence.

• Found that uranyl sulfate, K2UO2(SO4)2, could expose a photographic plate without being exposed to light.

• Found other uranium compounds did the same, even if they were known to be non-phosphorescent.

Phosphorescence vs Radioactivity

Properties of Radioactive Compounds

• Generally heavy atomic weight (Z < 82)

• Emission of several types of radiation• Penetration• Ionization• Deflection by an electric

field• For brevity, Becquerel

denoted the rays as α, β, and γ

The α-ray• Minimal

penetration• Slight

deflection from magnetic field

• Positively charged

• Charge-to-mass ratio is more than twice that of the canal ray (Proton)

The β-ray• Moderate penetrative

ability• Negatively charged• Very deflected by an

electric field• Charge-to-mass ratio

roughly equal to cathode rays (electrons)▫ Calculated by finding

the radius of curvature when passing through an electric field.

The γ-ray• Extremely penetrating• Not deflected by

electric field• Similar to X-rays, but

not as ionizing.• Exposure is

hazardous

Impact of Discovery

• More in-depth analysis of the nature of the nucleus

• Expansion of the periodic table

• Led to the invention of the atomic bomb

• Medical Imaging• Direct cause of death for

both Ernest Rutherford and Marie Curie

Future Applications

Bibliography• Henri Becquerel - Nobel Lecture: On Radioactivity, a New

Property of Matter". Nobelprize.org. Nobel Media AB 2013. Web. 2 Dec 2013. http://www.nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-lecture.html

• Ernest Rutherford. “Radio-activity”. 2nd edition, 1905. 24 Nov 2013

• http://chem-guide.blogspot.com/2010/04/radioactive-rays-alpha-ray-beta-ray.html

• DC/Marvel comics and 20th Century Fox

Questions?