GE Chapter 1. Historical Background Historical Background to the Study of Climate Change In the 19th century‚ scientists realized that gases in the atmosphere caused a "greenhouse effect" which affected the planet’s temperature. These scientists were interested in the possibility that a lower level of carbon dioxide gas might explain the ice ages of the distant past. At the turn of the century‚ Svante Arrhenius calculated that the emissions from human industry might someday bring a global warming
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TERM PAPER DONE BY: SUMEET SONI LECTURER: JAMES MUNYITHYA I.D NO: 637294 COURSE: NSC2215 TABLE OF CONTENTS TOPIC PAGE INTRODUCTION…………………………………………………………………………2 NUCLEAR REACTIONS……………………………………………………………….3 HOW IT WORKS…………………………………………………………………………5 BENEFITS OF NUCLEAR POWER STATIONS…………………………………9 DRAWBACKS OF NUCLEAR POWER STATIONS…………………………….10 CASE STUDY……………………………………………………………………………11 CONCLUSION…………………………………………………………………………
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ago and was preserved due to the low temperatures and permafrost that was present during that time. Tests such as “next generation” sequencing technology and isotopes analyses of carbon and nitrogen of past and present environments were used. The date of a split between the brown bear and polar bear was concluded to be a mean of 152 ky. Isotope data collected also proved that the polar bear morphologically and physiologically adapted at a very rapid
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Dinosaurs Were Endotherms Jiawei Tan‚ 30120159 Abstract: Whether dinosaurs were warm-blooded or cold-blooded is one of the most heated controversies since 19th century. This article is to suggest that dinosaurs were endotherms‚ which means they were warm-blooded. In this paper‚ I will list some evidences that indicate dinosaurs were more similar to mammals and birds rather than cold-blooded animals‚ such as reptiles. Evidences will be shown with comparison among dinosaurs‚ warm-blooded animals
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crust. The percentages of the halogens in the igneous rocks of Earth’s crust are 0.06 fluorine‚ 0.031 chlorine‚ 0.00016 bromine‚ and 0.00003 iodine. Astatine and element 117 do not occur in nature‚ because they consist of only short-lived radioactive isotopes. The halogen elements show great resemblances to one another in their general chemical behaviour and in the properties of their compounds with other elements. There is‚ however‚ a progressive change in properties from fluorine through chlorine‚
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so causing leukemia.<br><br>Plutonium appears very little in nature. It can be produced by bombarding uranium with the nucleus from a hydrogen ion. This hydrogen ion is called deuterium and so the nucleuses are called deuterons. There are 15 known isotopes of plutonium. They range from an atomic mass of 232 to 246. Plutionum-239 is thought to be the most important. It can be split into two parts called "fission fragments" that release large amounts of energy. It melts at 641 degrees Celsius and boils
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Atoms combine in whole number ratios to form compounds and if these proportions differ‚ so will the compound. However‚ the modern Atomic Theory provides evidence that disproves some of Dalton’s Theory: 1. Atoms of the same element can differ (isotopes and ions). 2. Atoms are divisible. we know atoms are made of smaller parts‚ and you can break them down in nuclear (not chemical) reactions‚ but overall Dalton set up a great base of knowledge for the next group of atomic scientists to build
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symbol is Os. Its atomic mass is 190.23 2. What is the elements atomic number‚ what class of elements does it fall into ▪ The atomic number for osmium is 76. Osmium falls into the transition metal group. 3. Are there any common isotopes of this element? ▪ Yes 4. Describe when‚ by whom and how the element was discovered ▪ Osmium was discovered in 1803 in England by Smithson Tennant. He discovered osmium in residue remaining when crude platinum was dissolved in aqua
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nucleus and cannot move from inside the nucleus. The proton symbol is . Neutrons are also located inside the nucleus and have a neutral charge. Neutrons are also one amu like protons. Neutrons can move from the nucleus of an atom making an atom an isotope. The neutron symbol is . Electrons are located outside the nucleus in energy levels. Electrons have a negative charge and weigh approximately 1/2000th of an amu. The weight is almost insignificant. Electrons can vary in an atom making cations
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efficient to use a spreadsheet such as Excel (or the Openoffice equivalent) to perform the calculations. 5. The Earth is about 4.5 billion years old. If 235 U is 0.72% abundant today‚ how abundant 92 was it when the Earth formed?. Note: Uranium isotope half lives and present day abundances: 234 2.455×105 y 235 7.038×108 y 238 4.468×109 y 0.006% 0.72% 99.27% 1
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