6.1.1 The Composition of the Nucleus

The Composition of the Nucleus

1. You have learned in chemistry that in an atom, electrons move around a central core called the nucleus.
2. The nucleus consists of protons and neutrons. It contains almost all the mass of the atom.
3. The nucleus of an atom is very small compared to the size of the atom
4. Protons and neutrons also are known as nucleons.

Nuclide Notation

1. Proton number is defined as the number of protons in a nucleus.
2. Nucleon number is defined as the total number of protons and neutrons in a nucleus. It is also known as the mass number.
3. A nuclide is a type of atom with a particular proton and nucleon number.
4. A nuclide can be represented by a nuclide notation that shows the symbol of the element, proton number and nucleon number.
5. The figure below shows the nuclide notation of nitrogen.

Isotopes

1. Isotopes are atoms of certain elements which have the same number of protons but different number of neutrons in the nucleus of the atoms.
2. It can also be defined as atoms of certain elements with the same proton numbers but with different nucleon numbers.
3. Isotopes have the same chemical properties but different physical properties.
4. The table below shows the proton and nucleon number of the isotopes of hydrogen and oxygen.