How do you write a balanced nuclear equation for alpha decay of Po-218?

1 Answer
Jul 11, 2017

Answer:

Here's how you can do that.

Explanation:

When a radioactive nuclide undergoes alpha decay, it emits an alpha particle, #""_2^4alpha#, which is essentially the nucleus of a helium-4 atom.

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This means that after the alpha particle is emitted

  • the mass number of the nuclide will decrease by #4# #-># this happens because the alpha particle contains #2# protons and #2# neutrons
  • the atomic number of the nuclide will decrease by #2# #-># this happens because the alpha particle contains #2# protons

You can thus say that you have

#""_ (color(white)(.)84)^218"Po" -> ""_ (color(white)(.)(84-2))^((218 - 4))"X" + ""_ 2^4alpha#

A quick look in the Periodic Table of Elements will show that the element that has the atomic number equal to

#84 - 2 = 82 -># conservation of charge

is lead, #"Pb"#. This means that the resulting nuclide will be lead-214 since its mass number is equal to

#218 - 4 = 214 -># conservation of mass

The balanced nuclear equation that describes the alpha decay of polonium-218 will look like this

#""_ (color(white)(.)84)^218"Po" -> ""_ (color(white)(.)82)^214"X" + ""_ 2^4alpha#

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