5.1. The nuclear model of the atom
A subsection of Physics, 5054, through 5. Nuclear physics
Listing 10 of 92 questions
An atom of one isotope of sodium contains 11 protons, 13 neutrons and 11 electrons. State the nucleon number (mass number) of this isotope. Explain why the number of protons is equal to the number of electrons in a neutral atom. A nucleus of this isotope undergoes radioactive decay by the emission of a beta-particle. State the energy change that occurs during radioactive decay. Complete the nuclear equation that represents this decay by filling in the appropriate numbers in the blank spaces. Na is the chemical symbol for sodium. Na β + Mg At the start of an experiment, the count rate due to a sample of this isotope of sodium is found to be 1200 counts per minute. This is shown on by a point plotted at time t = 0. The half-life of this isotope is 15 hours. On , draw a smooth line to show how the count rate is expected to change between t = 0 and t = 30 hours. t / hours count rate counts per minute Explain why readings taken in an actual experiment may not follow a smooth line. Determine the count rate due to this isotope 30 hours before the start of the experiment. count rate = In the space below, draw a labelled diagram of the apparatus used to measure the count rate of the radioactive isotope.
5054_s11_qp_21
THEORY
2011
Paper 2, Variant 1
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Two isotopes of carbon are carbon-12 and carbon-14. One of these isotopes, carbon-14, undergoes radioactive decay. Describe what is meant by radioactive decay. Carbon-12 has a proton number (atomic number) of 6 and a nucleon number (mass number) of 12. Complete Table 7.1 for a neutral atom of each of these two isotopes. Table 7.1 carbon-12 carbon-14 number of protons number of neutrons number of electrons A sample of carbon-14 is contained in a thin aluminium container of thickness 0.2 mm. Radiation from the sample is detected outside the container. When the thickness of the aluminium is increased to 6 mm, no radiation from the sample is detected outside the container. State the type of radiation which is stopped by increasing the thickness of the aluminium. Explain how you know that the sample does not emit one other type of radiation.
5054_s20_qp_21
THEORY
2020
Paper 2, Variant 1
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Questions Discovered
92