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igcse physics notesprinted 113 · PDF 113
124 pagesrevision 46936
printed 113 · PDF 113
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113
The atomic number, Z, of an element is the number of protons in the
nucleus of an atom of an element.
The nucleon number, A, of an element is the total number of protons and
neutrons in an element and is also known as the atomic mass.
Total number of neutrons in an atom= A-Z
The notation for an atom is AZX where A= Nucleon number, Z= Atomic
Number and X= Name of element.
Nuclear Fusion and Fission
Isotopes are atoms of the same element with the same proton number but
a different neutron number.
Nuclear fission is known as the splitting of nuclei whereas nuclear fusion is
the joining of nuclei.
Both these processes release large amounts of energy but the energy
released in fusion is much greater than that released in fission.
Example of equation of fission: 23592U + 10n → 9236Ba + 14156Kr + 3 10n+
energy
Example of equation of fusion: 21H + 21H → 32He + 10n
This energy is not created, rather it is the energy released due to a slight
decrease in mass of the particles which is converted to energy using
Einstein’s equation E=mc2
The relative charge on a nucleus is equal to the number of protons in the
nucleus because they each have a charge of +1
The nucleon number is the number of protons + neutrons and it is equal to
the relative mass of the nucleus since it contains only protons and
neutrons.