Nuclear Pt 1

A m u 3 ; 3 : : 3 : a , . 0 : s i a : ( D : 0 : m ; s : -IU -5 The radioactive nuclide 2i:Po decays by alpha-emission into a 4 Fig. 8.1 shows the position of Neptunium-231 (n;Np) on a diagram in which nucleon number (mass number) A is plotted against proton number (atomic number) Z. -A nuclide represented by th&symbol % Y is also radioactive, and decays by beta-and gamrna-emission to become a nuclide represented by Z. These processes are represented by equations 4.1 and 4.2. 2i,8Po d ;Y+;c( Equation 4.1 ;Y -/ez+pTp+y Equation 4.2 Complete Table 4.1 to give the numerical values of the quantities a, b, c, d, e,f, g and h. Table 4.1 Uranium-238 decays by alpha emission to thorium-234. The table shows the masses in atomic mass units, u, of the nuclei of aranium-238 ('i: U), thorium-234, and an alpha particle (helium-4). Quantity Value I Element /Nuclear massiu 1 I Helium-4, alpha particle I 4.00 15 1 c z b c c i e f g h Fig. 8.1 1 atomic mass unit, u = 1.7 x kg [dl (a) Neptunium231 decays by the emission of an a-particle to form protactinium. On Fig. 8.1, mark with the symbol Pa the position of the isotope of protactinium produced in this decay. [I] (i) How many neutrons are there in a uranium-238 nucleus? (1 mark) (b) Plutonium-243 (';:Pu) decays by the emission of a P-particle (an electron). (ii) How many protons are there in a nucleus of thorium? On Fig. 8.1, show this decay by labelling the position of Plutonium-243 as Pu and the position of the daughter product as D. 121 (1 mark) ...................................................................................... Determine the mass change in kg when a nucleus of uranium-238 decays by alpha emission to thorium-234.