When Thomson proposed his model, the presence of negatively charged electrons in the atom was known and an atom was known to be electrically neutral. Explain how Thomson’s plum pudding model takes account of these known facts. - In Thomson’s model the “plums” are the electrons and the pudding is positively charged matter, Rutherford investigated the atom by firing alpha particles through thin gold foil. He noticed the majority of the alpha particles passed right through the foil and that some of the alpha particles were deflected from their original path. - Rutherford found that an atom is mostly empty space., Rutherford also found that - Although most of the atom is empty space there must be a small charged piece of matter that causes the few alpha particles that happen to come close to it to be electrostatically deflected., Radon 222Rn86 is a radioactive gas occurring naturally in rocks and is responsible for much of the background radiation we experience the background radiation we experience.State the number of protons and neutrons, in the Radon nucleus. - Protons = 86, Neutrons = 136, When radioactive radon decays, it produces polonium 218Po84 and a radioactive particle. What type of radioactive particle is emitted and explain how you know this - An alpha particle is emitted. The decay reduces the mass number by 4 and the atomic number by 2 and the particle that has a mass number of 4 and atomic number of 2 is the helium nucleus. A helium nucleus is an alpha particle., During radioactive decay gamma radiation can be emitted from a radioactive nucleus. Describe two properties of gamma radiation that make its effect on us different from that of radioactive particle emission.  - Gamma radiation has much greater penetration ability and has much greater penetration ability, A fission reaction that occurs in a nuclear power plant is the result of the absorption of low energy neutrons by uranium235. When a uranium235 nucleus absorbs a neutron, it splits into two lighter nuclei. One example of such a reaction is - When a uranium235 nucleus absorbs a neutron, it splits into two lighter nuclei., .Use the equation to identify the other particle(s) produced during the reaction. - 235 + 1 – 137 - 95 = 4; 92 – 55 – 37 = 0; The only particle that has Z = 0 is the neutron. A neutron has A = 1, so there must be 4 neutrons,

Physics test 2

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