The diagram shows an atom of uranium-235 being split into several pieces. What is the name the process shown in the diagram? What is the name of the particles labelled X?

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1 Answer
Jan 6, 2017

Answer:

Here's what I got.

Explanation:

Let's start by identifying the particles labeled #"X"#.

As you know, nuclear reactions are characterized by the fact that

  • mass is conserved, i.e. the overall mass number of the ractants must be equal to the overall mass number of the products
  • charge is conserved, i.e. the overall atomic number of the reactants must be equal to the overall atomic number of the products

Now, notice that you have #1# particle labeled #"X"# on the reactants' side and #3# particles labeled #"X"# on the products' side.

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Grab a periodic table and look for the atomic numbers of uranium, #"U"#, krypton, #"Kr"#, and barium, #"Ba"#. You will find

  • #"For U: " -> "atomic number"= 92#

  • #"For Kr: " -> "atomic number" = 36#

  • #"For Ba: " -> "atomic number" =56#

If you take #A# to be the mass number and #Z# to be the atomic number of each particle #"X"#, you can say that

#""_color(darkgreen)(Z)^color(blue)(A)"X" + ""_color(darkgreen)(color(white)(1)92)^color(blue)(235)"U" -> ""_color(darkgreen)(36)^color(blue)(89)"Kr" + ""_color(darkgreen)(color(white)(a)56)^color(blue)(144)"Ba" + 3""_color(darkgreen)(Z)^color(blue)(A)"X"#

Now, you know that mass and charge must be conserved, which means that you can write

#color(darkgreen)(Z + 92 = 36 + 56 + 3Z)-># conservation of charge

This will get you

#92 = 92 + 2Z implies Z = 0#

You can also write

#color(blue)(A + 235 = 89 + 144 + 3A) -># conservation of mass

This will get you

#2 = 2A implies A = 1#

Therefore, you can say that the particle labeled #"X"# is a neutron, since it has no charge and a mass number equal to #1#.

#""_Z^A"X" = ""_0^1"n"#

The balanced nuclear equation will look like this

#""_ 0^1"n" + ""_ (color(white)(1)92)^235"U" -> ""_ 36^89"Kr" + ""_(color(white)(a)56)^144"Ba" + 3""_0^1"n"#

This nuclear equation describes the nuclear fission of uranium-235.

http://www.nuclear-power.net/nuclear-power/fission/