Nuclear Chemistry PDF

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De La Salle University – Dasmariñas

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nuclear chemistry radioactive decay atomic nuclei science

Summary

This document details nuclear chemistry, including radioactive decay, nucleons, nuclides, and isotopes. It also discusses the concept of isotopes and their differences and types. It includes the spontaneous emission of radiation, and the two ways to present nuclides.

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Module 5 Radioactive Decay Nuclear Chemistry ​ The spontaneous emission of ​ Branch of Chemistry radiation ○​ the study of atomic nuclei ○​ Result from the change in and t...

Module 5 Radioactive Decay Nuclear Chemistry ​ The spontaneous emission of ​ Branch of Chemistry radiation ○​ the study of atomic nuclei ○​ Result from the change in and the changes it the nuclei of the atom undergoes. element. Wilhelm Conrad Roentgen Nucleons ​ Began the study of Nuclear ​ Protons and neutrons of a nucleus. Chemistry ​ He discovered X-ray in 1895 Nuclides ​ Is a nucleus with particular Antoine Henri Becquerel number of protons and neutrons ​ He studies Phosphorescence ​ Can be presented in Two ways: ○​ Made an investigation in ○​ By showing the element’s relation of X-ray to his symbol with its mass study. number and atomic ​ Accidentally discovered that number. uranium salts emit radiation on a ○​ By writing the element’s photographic plate. name followed by a hyphen ​ Proved that the phenomenon was and its mass numbers. new and not X-ray radiation. Isotopes Marie Curie ​ Each element has different ​ Continued the study of uranium nuclides. rays ​ Are atoms of the same element that ○​ Later named the have different numbers of phenomenon neutrons. “radioactivity”. ​ Have the same atomic number but different mass number. Pierre and Marie Curie ​ Are husband and wife Two Types of Isotopes: ​ Discovered the radioactive ​ Stable Isotopes elements: ○​ Atoms that do not release ○​ Radium (Ra) and Polonium protons or neutrons from (Po). the nucleus. ○​ Not radioactive. Nobel Prize in Physics ​ Unstable Isotopes ​ Peirre and Marie Curie with ○​ Atoms that spontaneously Becquerel in 1903. release protons and neutrons from its nucleus. 20th Century ○​ Is Radioactive. ​ Lot of radioactive substances were discovered leading to more Strong nuclear force developed and understanding of ​ Held together the nucleus of an radiation and nuclear decay. atom at small distances ​ To prevent Electrostatics. ​ Gamma decay Electrostatic ○​ When the nucleus emits a ​ Repulsion of protons from blowing high energy form of apart the nucleus. electromagnetic radiation. ​ Results when Nucleus nucleus decay from ​ When the number of protons an excited state to a increases, the number of neutrons lower state, photons must increase to be stable. emitted by electrons ​ Too many or few neutrons causes returning to a lower imbalance between these forces state. leading to an unstable. ○​ Identity of the parent nuclide does not change Radioactive isotopes because no particle ms are ​ Will emit particles and energy from physically emitted. its nucleus to become more stable. ○​ More penetrating ○​ Stopped by several inches Radiation of lead, steel, or concrete. ​ Emitted energy and particles. ​ Positron emission ○​ The conversion of protons Types of Radioactive Decay into neutrons with the ​ Alpha decay emission of positron. ○​ Two protons and two ○​ Positron is the same as neutrons or a helium electron mass but opposite nucleus are emitted from charge. the nucleus of the parent ​ Electron Capture atom. ○​ When an unstable proton ○​ Not hazardous outside the rich or neutron deficient body. nucleus draws in a ○​ Cause damage when surrounding electron ingested. (usually one from the ○​ Stopped by a piece of lowest energy level). paper. ○​ The Capture combines with ​ Beta decay a proton to form a neutron. ○​ When the nucleus contains ○​ As a consequence, the too many neutrons. atomic number of the ○​ Neutron from the nucleus nucleus decreases by one. is transformed into a proton and an electron with Rate of Radioactive Decay the electrons ejected from ​ Found to be proportional to the the nucleus. number of radioactive nuclei in the ○​ Have the same charge and sample. mass as electrons. ○​ More Hazardous if inhaled or ingested. ○​ Stopped by a few Half life millimeters or aluminum or a layer of clothing. ​ A radioactive sample decay at a of certain radioactive nuclides constant rate and this rate is presented. measured. ○​ Carbon-14 is most common ​ The time required for the number used to estimate the age of of nuclides to reach half of its organic materials up to original value. 50,000 years old. Energy changes in Nuclear Decay Cobalt-60 ​ Radioactive nuclide Mass Defect ​ Used in the field of medicine as a ​ Also called as Mass difference. radioactive tracer. ​ The loss in mass that occurs when protons and neutrons combine to form a nucleus. ​ The difference between the total mass of the separate nucleons Module 6 added together compared to the mass of the nucleus when all the Fuel nucleons are together in the ​ Substances that burn to release nucleus energy. ​ Exothermically react with oxygen Nuclear Fission in a process called combustion. ​ When a heavy nuclei split into two ​ Contains carbon and hydrogen as or more smaller nuclei with some main combustible elements. subatomic particles and energy. ​ Importance; ​ Usually Does not occur naturally, ○​ Mainly used for generating most happen artificially by electricity to run machines bombarding a nuclei with and appliances; neutrons. manufacturing; heating and cooling; transportation and Chain reaction cooking. ​ Neutrons release in induced ​ To remember; reaction can then trigger more ○​ Combustion products are reactions on other Uranium-235. always carbon dioxide and water Nuclear Fusion ○​ Fuel is not created equal. ​ The combination of two light nuclei forming a heavier nuclei Characteristic of Good Fuel releases enormous amounts of 1.​ Easily ignited in air at a reasonable energy. degree. ​ To fuse or combine two nuclei, a 2.​ Have high specific heat meaning it large amount of heat energy and produces a lot of heat. high pressure are required. 3.​ Have low content of non-combustible materials in the Radiocarbon dating form of ash. ​ The process by which the 4.​ Not produce harmful products approximate age of an object is which adversely affect the determined based on the amount environment. 5.​ Low cost. Coal 6.​ Easy storage and transportation. ​ A fossil fuel 7.​ Low moisture and ash content. ​ Is considered as the largest source of energy as well as the primary Classification of fuels source of carbon dioxide emissions ​ can be classified based on their worldwide. physical state and occurence. ○​ Physical state How is coal formed? ​ Fuel is categorized -​ formed from plants remains whose as solid, liquid. and physical and chemical properties gas. were transformed by ○​ Occurrence environmental action to form solid ​ They are grouped as materials. primary, natural ​ Steps in formation of coal and secondary or ○​ Formation of peat; prepared. ​ Organic matter from plants Primary Fuel accumulates in ​ Naturally occurring such as coal, swamps. crude oil, and natural gas. ​ Then, as the plant ​ Can be mined, reaped, extracted, dies and is buried, it harvested or harnessed directly. becomes peat. ​ Commonly referred to as fossil ○​ Formation of Lignite; fuels. ​ Volatile compounds ○​ Where approximately 85% like water and of the world's energy comes methane is driven from. off by the ○​ Is the major cause of compaction of peat carbon dioxide emissions, due to burials Thus one of the greenhouse gases soft-brown colored that triggers global organic-rich coal warming. called lignite is formed. Secondary Fuel ​ Contains 20-30% of ​ Originated from primary or carbon and 60% naturally occurring ones through moisture different physical or chemical ​ Does not burn processes. efficiently. ​ Such as charcoal, petrol, and LPG. ○​ Formation of bituminous coal Solid Fuel ​ Further compaction ​ First one ever used by man in early and heating results civilization. in a more ​ Are cheap, readily available, simple carbon-rich coal. to mine and easy to ship. ​ Contains about 85% ​ Non renewable resources since it carbon. takes thousands of years to form. ​ Readily burns but ​ Prepared by burning woods and generates a lot of sometimes animal matter and smoke. extinguishing fire just before they ○​ Formation of anthracite turn into ash. coal ​ The carbon combines with oxygen ​ A high grade coal producing carbon dioxide, carbon ​ Formed when rock monoxide, water, other gases and a undergoes significant amount of energy when metamorphism. ignited. ​ Dark hard coal ​ Consist 90-95% Liquid Fuels carbon and burn ​ Originated from fossilized deposits cleanly. of dead plants and animals by ​ Has high heat exposure to heat and pressure in content and low earth’s crust. sulfur content. ​ Vapors from the liquid are Importance of Coal flammable and not the liquid itself. ​ Is used to generate steam which is ​ Burn without dust and ash used for running turbines to ​ Easy to transport through pipes. generate electricity in power ​ Highly flammable and volatile plants. ​ Need special storage containers ​ One of the most abundant fuel in ​ Yield bad odors nature ​ Inexpensive and easily Crude oil transported. ​ Naturally occurring ​ Unrefined petroleum made of Downside of coal hydrocarbon deposits and other ​ Non renewable resources organic substances. ​ Creates environmental problems ​ Trapped in sendimentary rock in like excessive carbon dioxide earth’s crust At varying pressures emissions. depending on depth. ​ Coal mining affects land and is ​ Collected using offshore drills considered dangerous. ​ Refined to usable petroleum products. Coke ​ Obtained when coal is heated Refined Petroleum Products strongly in the absence of oxygen in a process called carbonization or coking. ​ Has high carbon content ​ Low ash and sulfur content ​ Very highly priced in market ​ Used in industries requiring uniform heating and high temperature. Charcoal ​ Is man-made product

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