State how the structure of a helium atom is different from the structure of the helium ion.
State how the structure of an alpha-particle is different from the structure of the helium ion.
A thorium-229 nucleus ($^{229}_{90}\\text{Th}$) undergoes alpha ($\\alpha$) emission and becomes a nucleus of element X.\n\n$^{229}_{90}\\text{Th} \\rightarrow X + {}^{4}_{2}\\alpha$\n\nThe X nucleus then undergoes beta ($\\beta$) emission to form a nucleus of Y.\n\n$X \\rightarrow Y + {}^{0}_{-1}\\beta$\n\nComplete Table 9.1 to show the number of protons and neutrons in a nucleus of X and in a nucleus of Y.
Experiments can demonstrate that a sample of a material is radioactive.\n\nDescribe the apparatus and the procedure used to demonstrate that a sample emits both alpha-particles and beta-particles.\n\nYou may draw a diagram of the apparatus, if you wish.
State the meaning of the half-life of thorium-229.
A pure thorium-229 sample contains $4.0\\times10^{14}$ atoms. After $22\\,000$ years, the sample contains $5.0\\times10^{13}$ thorium-229 atoms.\n\nDetermine the half-life of thorium-229. Show your working.