AQA GCSE Chemistry Unit 1 C 1: Fundamental ideas: C 1.1. Atoms‚ elements and compounds: * All substances are made up of atoms. * Elements contain only one atom. * Compounds contain more than one atom. * An atom has a tiny nucleus in its centre‚ surrounded by electrons. C 1.2. Atomic structure: * Atoms are made up of protons‚ neutrons and electrons. * Protons and electrons have equal and opposite electrical charges. Protons are positively charged‚ and electrons are negatively
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Cooling Water Problems and Solutions Course No: M05-009 Credit: 5 PDH A. Bhatia Continuing Education and Development‚ Inc. 9 Greyridge Farm Court Stony Point‚ NY 10980 P: (877) 322-5800 F: (877) 322-4774 info@cedengineering.com COOLING WATER PROBLEMS AND SOLUTIONS Water is used in cooling systems as a heat transfer medium and frequently also as the final point to reject heat into the atmosphere by evaporating inside cooling towers. Depending on the quality of available fresh
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of anthropogenic pollutants. There are a number of chemical reactions that can deplete stratospheric ozone; however‚ some of the most significant depletion comes from the catalytic destruction of ozone by freed halogen radicals like chlorine and bromine. Overview of Ozone Depletion Ozone depletion is term used to describe occurrences regarding the Earth ’s ozone layer. One of these observable trends is the slow and constant deterioration of the ozone in the atmosphere of about three percent
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Surname Centre No. Initial(s) Paper Reference 4 3 3 5 Candidate No. 2 H Signature Paper Reference(s) 4335/2H Examiner’s use only London Examinations IGCSE Team Leader’s use only Chemistry Paper 2H Higher Tier Wednesday 17 June 2009 – Morning Time: 2 hours Materials required for examination Nil Items included with question papers Nil Question Leave Number Blank 1 2 3 4 5 6 7 8 9 Instructions to Candidates In the boxes above‚ write your centre number‚ candidate number‚ your surname
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Ba h. 7.1 Ions 27. What is a valence electron? * 28. To which group in the periodic table does each of the following elements belong? How many valence electrons do atoms of each element have? a. nitrogen d. barium b. lithium e. bromine c. phosphorus f. carbon 37. Name each ion in Problem 36. Identify each as an anion or a cation. 7.2 Ionic Bonds and Ionic Compounds 38. Define an ionic bond. 39. Explain why ionic compounds are electrically 29. Write electron dot structures
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Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39.10 40.08 44.96 47.87 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.38(2) 69.72 72.63 74.92 78.96(3) 79.90 83.80 37 38 39 40 41 42 43 44 45 46 47
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carbon has a molar mass of 12.01 grams per mole.There are a few exceptions to this rule. In some cases‚ the element is usually found in a different form than just one unbonded atom. In the case of hydrogen‚ nitrogen‚ oxygen‚ fluorine‚ chlorine‚ bromine‚ and iodine‚ the element is diatomic‚ meaning that each molecule of the element has two atoms of that element stuck together. As a result‚ the formula of hydrogen is H2‚ nitrogen is N2‚ etc.This gets weirder for a couple of cases... phosphorus is normally
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Melissa Kenney Dr. Braun/Lab K Lewis Symbols & Structures Purpose The purpose of this lab experiment is to practice writing Lewis symbols for elements and monatomic ions while writing Lewis structure for molecules and polyatomic ions. I will also be writing chemical equations using Lewis structures for
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Unsaturated Hydrocarbons Unsaturated hydrocarbons Have fewer hydrogen atoms attached to the carbon chain than alkanes. Are alkenes with double bonds. Are alkynes with triple bonds. 1 Structure of Alkenes Alkenes (and alkynes) are unsaturated hydrocarbons Alkenes have one or more double bonds The two bonds in a double bond are different: - one bond is a sigma () bond; these are cylindrical in shape and are very strong - the other is a pi (π) bond; these involve sideways overlap of
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NUTRIENTS IN BANANA PEELS Banana peels are also rich sources of potassium and contain much more soluble and insoluble fiber than their flesh. Dietary fiber promotes digestion and bowel movements and can reduce blood cholesterol levels. Banana peels also contain tryptophan‚ which increases serotonin levels in the body and affects mood‚ much like the drug Prozac does. According to "Prescription for Nutritional Healing‚" researchers in Taiwan discovered banana peel extract can ease depression because
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