Nuclear Reactions and Conservation Laws
Nuclear equations
What is a nuclear reaction?
A nuclear reaction is a process in which one nucleus changes into another nucleus, often by being hit by a particle or by splitting or combining with another nucleus.
Conservation laws
In nuclear reactions, physicists usually conserve electric charge, total nucleon number, and energy. Momentum is also conserved.
Balancing equations
To balance a nuclear equation, make sure the total mass number and total atomic number are the same on both sides.
Example pattern
If a nucleus emits an alpha particle, the mass number decreases by and the atomic number decreases by .
How to balance a nuclear equation
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1
Write the nuclei and particles on both sides.
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2
Add up mass numbers on each side.
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3
Add up atomic numbers on each side.
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4
Fill in the missing particle or nucleus so both sides match.
Which quantity must be conserved in a balanced nuclear equation?
Nuclear equations are balanced by conserving mass number and atomic number.
Correct answer: Mass number and charge
What two numbers are used to balance most nuclear equations?
These correspond to nucleon count and charge.
Correct answer: mass number and atomic number
If a nucleus undergoes alpha decay, how do and change?
An alpha particle contains 2 protons and 2 neutrons, so those numbers leave the nucleus.
Correct answer: decreases by 4 and decreases by 2