What is a nuclear reaction? What is Unified Atomic Mass Unit/Mass Defect/Nuclear Fission/ Nuclear Binding Energy and nuclear power in general? Easy nuclear reaction infographic guide/review to study for your IB Physics SL/HL exams.

## DID YOU KNOW?

Nuclear Reactions

The first induced nuclear reaction was accomplished by famous Australian physicist Ernest Rutherford, the same physicist who actually founded the nuclear structure of the atom and successfully bombarded atoms with alpha particles. Let’s look at the first nuclear reaction:

# Unified Atomic Mass Unit

The __unified atomic mass unit__ is the standard used to indicate a unit of mass in the atomic or molecular scale. A unit of unified atomic mass unit is measured in ** u** or

**equal to 1/12 of the mass of carbon-12**

*Da*

1 u or Da in: |
Equals to: |

kg |
1.660539040(20)×10^{−27} |

MeV/c^{2} |
931.494095(11) |

m_{e} |
1822.88839 |

# Mass Defect and nuclear binding energy

To understand nuclear reactions we have to use Einstein’s mass-energy equivalence relationship:

* *

*E* = *mc*^{2} means is that **mass and energy are interchangeable**.

## Mass Defect

Mass Defect (∆*m*): The difference in mass between the reactants and the products.

Three steps to find __Mass defect__ of a nuclear reaction:

(1) Find the mass of the reactants added together to create the product’s mass.

(2) Find the mass of the product only.

(3) Find the difference in mass (product mass – reactants mass).

EXAMPLE: Label the reactants and the products in the following nuclear reaction: 2(^{1}H) + 2n ® ^{4}He.

SOLUTION:

2(^{1}H) + 2n ® ^{4}He

Reactants product

# Nuclear Binding Energy

Binding energy (*E _{b}*): The amount of work or energy required to be applied to a nucleus before it can be broken down into its component nucleons.

Finding __binding energy:__

**E _{b} = mc^{2 }**

E_{b} = binding energy

m = mass defect of reaction in kilograms

c = speed of light (3.00´10^{8})