Conservation of Nucleon Number & Charge
- Nuclear processes such as fission and fusion are represented using nuclear equations (similar to chemical reactions in chemistry)
- The number of protons and neutrons in atom is known as its constituents
- For example:
- The above equation represents a fission reaction in which a Uranium nucleus is hit with a neutron and splits into two smaller nuclei – a Strontium nucleus and Xenon nucleus, releasing two neutrons in the process
- In nuclear equations, the nucleon number and charge are always conserved
- This means that the sum of the nucleons and charge on the left hand side must equal the sum of the number of nucleons and charge on the right hand side
- In the above equation, the sum of the nucleon (top) numbers on both sides are equal
235 + 1 = 236 = 90 + 144 + 2 × 1
- The same is true for the proton (bottom) numbers
92 + 0 = 92 = 38 + 54 + 2 × 0
- By balancing equations in this way, you can determine the nucleon, proton number or the number of missing elements
- Let's consider another example:
- Determine the total nucleon number
- This is determined from the side of the equation where all the values are known
- In this example, from the reactants
-
- The total nucleon number = 235 + 1 = 236
- Equate the total nucleon number to the total nucleon number of the products including the unknown N
-
- Total nucleon number of reactants = 96 + 137 + (N ×1) = 236
- Rearrange to solve for N
- Balancing the equation shows that 3 neutrons must be released in the reaction
Worked example
When a californium atom reacts with an unknown element X, the following reaction occurs.
Determine the missing values of Y and Z.
Answer:
Step 1: Identify what the value of Y represents
- Y is the proton number of element X
Step 2: Determine the value of Y
- Determine the number of protons on both sides of the equation
Step 3: Identify what the value of Z represents
- Z is the nucleon number of the element Lr
Step 4: Determine the value of Z
- Determine the total nucleon numbers on both sides of the equation