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Rev. Notes > IGCSE > Radioactivity
 
 
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Radioactivity and radioactive - rays

Experiment to distinguish three kinds of radioactive rays Background radiations
Alpha rays Beta rays Gamma - rays
Radioactive decay

Half - life

Safety precautions

Isotopes

The radioactive isotopes Uses of radioactive isotopes
Uses of radioactive isotopes - Medicines Uses of radioactive isotopes - Industries Uses of radioactive isotopes - Agriculture
Uses of radioactive isotopes - Carbon dating Artificial radioactivity
 

Half - life

As we know that radioactive elements continuously emit radiations. As a result they get transformed into new elements.

The elements emitting radiations is known as parent element and the element formed as a result of the emission of radiation is called daughter element.

The time interval in which half of the atoms of the parent element in any given sample decay into daughter elements is known as the half life of the parent element.

Thus if we start with a sample of 100,000 atoms of a radioactive element with a half life of T (e.g. 5 days), then after a lapse of T time (5 days), 50,000 atoms of the element will decay into daughter element.

After the lapse of another period of time T(5 days) -"after total 10 days"-, the number of atoms of parent element will reduce to 25,000 and so on.

Different radioactive materials have different half lives which may range from thousands of years to a fraction of second.

 
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View Comments on this Chapter - Total Comments (16)
 
Chandiya Said :
THis is awesone and really really useful
 
  01/11/16 07:16 PM
   
Muhammad Hasnain Said :

Great work, please keep it up!

 
  10/07/15 04:07 PM
   
yas Said :
it says that the 3 types of radioactive rays can be distinguished from one another by a simple experiment but what is the experiment?
 
  13/04/15 11:10 PM
   
Sc Said :
Btw this is a great website :-)
 
  01/04/14 08:12 PM
   
Sc Said :
Where are the figures?
 
  01/04/14 08:00 PM
   
jjanedan Said :
Manufacturer of slip rings. We commit to the development, design, and marketing of high-quality. Main products include slip ring, ring slip, slip rings,slipring,rotary joint and so on. collector rings http://www.electricslipring.com/
 
  15/11/13 09:20 AM
   
julia kobeissi Said :
in isotopes , you said in thr figure below and theres no figure ?
 
  05/06/13 12:17 PM
   
Ryouta Said :
What is the charge on Beta particles then????? Coz Alpha have 2 charge, and Gamma are neautral...
 
  21/03/13 10:27 AM
   
kainat Said :
all the radium formed when the earth condensed out of the suns atmosphere should have decayed away to an unmeasurably small amount by now. why?
 
  02/09/12 03:09 PM
   
burhanuddin Said :
i have my mocks on monday < will dis help me?
------------------------------------------------------------------------------------- Admin Replied:

Definitely, it will help you.

 
  11/08/12 09:45 PM
   
Mohammad Said :
Can you give the definition for ionization
 
  13/05/12 08:44 PM
   
Frank Said :
It says "Carbon-1" somewhere in the beginning. Do rectify it.
------------------------------------------------------------------------------------- Admin Replied:

Thanks for your comments. Now that is rectified.

 
  24/01/12 07:12 PM
   
Sagnik Said :
If elements with the atomic mass of >84 are the only elements that undergo radioactivity, then explain how Carbon-14 can undergo radioactive decay.
------------------------------------------------------------------------------------- Admin Replied:

Stability of a nucleus depends upon the neutron/proton ratio. If this ratio is too small or large, the nucleus will be unstable. The neutron/proton ratio in carbon-14 is too large, making the nucleus sufficiently unstable that it emits a beta particle, converting to nitrogen-14.

Same situation of unstability is there in the elements having atomic number greater than 82.smiley

 
  24/01/12 07:01 PM
   
Swaira Said :
undefined
 
  01/11/11 07:14 PM
   
Abdullah Said :
What is the speed of light?
------------------------------------------------------------------------------------- Admin Replied:

Speed of light is 299 792 458 m / s

 
  31/10/11 06:41 PM
   
Hadaya Said :
What is the mass of the proton and alpha particle?
------------------------------------------------------------------------------------- Admin Replied:

Mass of a proton = 1.66 x 10^-27kg Mass of neutron = 1.6749 x 10^(-27) kg The rest mass of the alpha particle (which is equal to the mass of two protons and two neutrons) amounts to 6.64424 x 10^-27 kg.

 
  31/10/11 06:13 PM
 

 

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