OCR supplied materials: None Other materials required: • Scientific or graphical calculator • Geometrical instruments • Tracing paper (optional) * A 5 0 1 0 1 * INSTRUCTIONS TO CANDIDATES • • • • • • • Write your name‚ centre number and candidate number in the boxes above. Please write clearly and in capital letters. Use black ink. HB pencil may be used for graphs and diagrams only. Answer all the questions. Read each question carefully. Make sure you know what you have to do before starting
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THE REAL NUMBER SYSTEM The real number system evolved over time by expanding the notion of what we mean by the word “number.” At first‚ “number” meant something you could count‚ like how many sheep a farmer owns. These are called the natural numbers‚ or sometimes the counting numbers. Natural Numbers or “Counting Numbers” 1‚ 2‚ 3‚ 4‚ 5‚ . . . * The use of three dots at the end of the list is a common mathematical notation to indicate that the list keeps going forever. At some point‚ the
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Quite a few scientists have helped to create and extend ideas on what an atom is and what its components are. One of these discoverers‚ John Dalton‚ developed the first modern atomic theory. Although much of his theory is still true today‚ one point was disproved by Ernest Rutherford. Dalton’s atomic theory had several parts to it. He believed atoms were indivisible‚ or impossible to break down into smaller particles. Also‚ he said elements are all consisted of atoms and that the atoms of
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Electrons surround the nucleus Number of neutrons = (protons & neutrons) mass number – atomic number #26 – 28 are key points 26. What distinguishes the atoms of one element form the atoms of another? Elements are different because they contain different numbers of protons. 27. How do the isotopes of a given element differ from one another? Isotopes of an element have different numbers of neutrons‚ they also have different mass numbers. 28. How is atomic mass calculated? Multiply the
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Joy Jenkins Changing of the periodic table Today‚ the periodic table organizes the elements in horizontal rows‚ or periods‚ by order of increasing atomic number. The elements are also organized in vertical columns‚ or groups‚ based on similar physical characteristics and chemical behavior. I believe the periodic table will continue to evolve as new elements are discovered. One of the earliest attempts to organize the elements based on their chemical and physical properties was made by German
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accurate positioning of elements in the Periodic Table by closer determination of atomic numbers. * He observed and measured the X-ray spectra of various chemical elements obtained by diffraction in crystals. Through this he discovered a systematic relation between wavelength and atomic number. This discovery is now known as the Moseley’s law. Moseley also predicted a number of missing elements and their periodic numbers in the Periodic Table. Moseley’s law is an empirical law concerning the characteristic
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universal precautions. Suppose the spread of a direct contact disease in a stadium is modeled by the exponential equation P(t) = 10‚000/(1 + e3-t) where P(t) is the total number of people infected after t hours. (Use the estimate for e (2.718) or the graphing calculator for e in your calculations.) 1. Estimate the initial number of people infected with the disease. Show how you found your answer. Answer: A total of 474 people would be initially infected. Equation: p(0)=10‚000/(1+3^3) ~ 474
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Assignment Chapter 2 Concept Explorations 2.25. Average Atomic Mass Part 1: Consider the four identical spheres below‚ each with a mass of 4.00 g. a. Calculate the average mass of a sphere in this sample. (4.00 + 4.00 + 4.00 + 4.00)/4= 16.00/4= 4.00g Part 2: Now consider a sample that consists of four spheres‚ each with a different mass: blue mass is 4.00 g‚ red mass is 3.75 g‚ green mass is 3.00 g‚ and yellow mass is 1.25 g. * a. Calculate the average mass of a sphere in this sample
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CHM130 Lab 5 The Atomic Mass of Beanium Name: Paige Miller A. Data Table: Insert your Data Table here with your sample calculations. You must show at least one sample calculation per procedure step. (16 points) Part I Data Table Sample Mass (mg) Number/Qty Average Mass (mg) Relative Abundance Relative Weight (mg) Kidneybeanium 1660.00 mg 3 553.33 mg 0.2143 118.58 mg Pintobeanium 2830.00 mg 6 471.67 mg 0.4286 202.16 mg Blackeyedpeaium 1110.00 mg 5 222.00 mg
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THE PERIODIC TABLE HISTORICAL BACKGROUND The idea that all things are elements or combinations of elements can be found in the writings of the ancient Greeks and other early peoples. Although this idea may seem simple‚ it is very difficult to decide if a substance is indeed an element or a compound. There were twelve chemical elements discovered in ancient times‚ but it was not known that they were elements. Another 76 elements were discovered between 1557 and 1925. Many mistakes were made in
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