Radioactivity

Henri Becquerel (1852-1908)

 Discovery

the phenomenom of natural radioactivity

Marie Curie (1867-1934) y Pierre Curie (1859-1906)

They studied radiactive materials, particularlyUranium in Pechblenda form  Pechblenda is more radoactive than Uranium, so there could be elements in Pechblenda that makes it more radioactive  They discovered to chemist elements: Radium and Polonium Pierre has an accident with horses and died  Marie died because of the radioactivity


 Dark

room  Cathodic rays tube enfolded (with black paper) and turned on  Cardboard with barium saltThe cathodic rays tube lets out an invisible ray, this ray pass over the black paper, reach the table and makes that the barium salt cristals shine on the dark If the cathodic rays tube goes off,theres no shine on the cristals

It shining althought were inteject various materials like books, paper, wood, glass, rubber, aluminium, a hand!!  The rays are not affected by magnetic fields  Theserays produce pictures in photographic plates  So the CRT emit a new type of invisible ray that do not contains electric particles, it can pass over objects and produce pictures  This new type ofradiation is called “X rays”


 Fluorescence:

emision of light by certain chemical substances if they are exposed to the sun light----PITCHBLENDE  Emit X rays these fluorescent substances…..? And produce they photographic impresions…?

 OBSERVATIONS

 Pitchblende

emit radiation of high energy even in the dark!! And print pictures  The Pitchblende “Uranium” emits spontaneously ahigh energy radiation called RADIOACTIVITY!!

Lead box

(+)
β rays γ rays α rays Radioactive (-)

Electrically charged plates

Photographic plate

 Rutherford

had designed anexperiment to study how alpha particles interact with thin metal foils
Fluorescent screen Lead box Thin gold foil

Radioactive

Alfa particles

 The

atom is like a “raisin puddin”, the poddin...