Chemistry_Grade_10-12 (1).pdf

Step 2 calculate the atomic number z and atomic mass

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Step 2 : Calculate the atomic number (Z) and atomic mass number (A) of the element that is formed. Z = 95 4 = 91 A = 241 4 = 237 Step 3 : Refer to the periodic table to see which element has the atomic number that you have calculated. The element that has Z = 91 is Protactinium (Pa). Step 4 : Write the symbol for the element that has formed as a result of radioactive decay. 237 91 Pa Step 5 : Write an equation for the decay process. 241 95 Pb 237 91 Pa + 2 protons + 2 neutrons Activity :: Discussion : Radiation In groups of 3-4, discuss the following questions: Which of the three types of radiation is most dangerous to living creatures (including humans!) 111
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7.4 CHAPTER 7. ATOMIC NUCLEI - GRADE 11 What can happen to people if they are exposed to high levels of radiation? What can be done to protect yourself from radiation (Hint: Think of what the radiologist does when you go for an X-ray)? Exercise: Radiation and radioactive elements 1. There are two main forces inside an atomic nucleus: (a) Name these two forces. (b) Explain why atoms that contain a greater number of nucleons are more likely to be radioactive. 2. The isotope 241 95 Pb undergoes radioactive decay and loses three alpha particles. (a) Write the chemical formula of the element that is produced as a result of the decay. (b) How many nucleons does this element contain? 3. Complete the following equation: 210 82 Am (alpha decay) 4. Radium-228 decays by emitting a beta particle. Write an equation for this decay process. 5. Describe how gamma decay differs from alpha and beta decay. 7.4 Sources of radiation The sources of radiation can be either natural or man-made . 7.4.1 Natural background radiation Cosmic radiation The Earth, and all living things on it, are constantly bombarded by radiation from space. Charged particles from the sun and stars interact with the Earth’s atmosphere and magnetic field to produce a shower of radiation, mostly beta and gamma radiation. The amount of cosmic radiation varies in different parts of the world because of differences in elevation and also the effects of the Earth’s magnetic field. Terrestrial Radiation Radioactive material is found throughout nature. It occurs naturally in the soil, water, and vegetation. The major isotopes that are of concern are uranium and the decay products of uranium, such as thorium, radium, and radon. Low levels of uranium, thorium, and their decay products are found everywhere. Some of these materials are ingested (taken in) with food and water, while others are breathed in. The dose of radiation from terrestrial sources varies in different parts of the world. Interesting Fact erest Fact Cosmic and terrestrial radiation are not the only natural sources. All people have radioactive potassium-40, carbon-14, lead-210 and other isotopes inside their bodies from birth.
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