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# NUCLEUS

CONTENT

1. Structure of an Atom
5. Half Life and Decay Constant
6. Nuclear Energy
7. Nuclear Reactions
8. Nuclear Reactors
9. Solved Problems
10. Nigeria Nuclear Energy Program

## Structure of an Atom

As discussed earlier, the modern atom model is the electron-cloud model which considers an atom as consisting of nucleus with electrons moving rapidly around the nucleus and spending most of their time in high probability region. The nucleus of an atom consists of a positively charged proton and neutron which has no charge. The electrons revolve round the nucleus.

Hydrogen, the simplest atom has one proton in its nucleus and one electron in its orbit. The next is helium atom which has two protons and two neutrons in it nucleus and two electrons in its is orbits

Proton and neutron are both called Nucleon because they can be found in the nucleus of an atom.

$$Z$$ is used to represent the number of proton in the nucleus and it is called the atomic number.

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