(a) Explain: (i) nuclear fission; (ii) nuclear fusion.
(b)(i) State three applications of atomic energy.
(ii) Define State. life.
(iii) Give the expression that relates the halflife, T, and the decay constant, X, of a radioactive material.
(c) A radioactive element X with atomic number 88 and mass number 226 emits in succession:
(i) an alpha particle, (ii) a beta particle and (iii) gamma radiation. Explain, using equations where necessary, the changes that take place in the atomic structure of the element at each stage.
Explanation
a)(i) Nuclear fission is a nuclear reaction in which a heavy nucleus is split into different lighter nuclei emitting neutrons with the release of a large amount of energy.
(ii) Nuclear fusion is a nuclear reaction between two light nuclei at high temperatures formic a heavier nucleus with the release of a large amount of energy.
(b)(i) Applications of atomic energy are:
- for the production of nuclear weapons for warfare
- in the generation of electric power
- for health diagnosis and radiotherapy
- to detect leakages. In underground pipes carrying oils or gases.
(ii) Half life is the time required for radioactive substance to decay to half of its original quantity.
(iii) T = \(\frac{0.693}{\lambda}\)
(c)(i) \(^{226}_{88} X \) ---> \(^{222}_{88} Y + ^4_2He\)
By the emission of \(\alpha\) the mass number of X decreases by 4 the atomic number by 2 to give daughter nucleus Y
(ii) \(^{222}_{86} Y \) ---> \(^{222}_{87} Z + ^0_{-1} e\)
By the emission of \(\beta\) particle the mass number of Y is unchanged while the atomic number of Y is unchanged while the atomic number is increased by 1.
(iii) \(^{226}_{87} Z \) ---> \(^{222}_{87} Z + ^0_0\gamma\) By emission of \(\gamma\) radiation, the mass and atomic number of Z remain unchanged.