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Name ______________________________________________ Chemistry Analyzing Trends in Data – Atomic Radius Date ____________ Period __________ Introduction Mendeleev noticed that when the elements were arranged in order of increasing mass, chemical properties repeated periodically. This periodicity was the first observation leading to the organization of the Periodic Table of the Elements. Following Mendeleev, Moseley showed that periodicity was related to atomic number rather than mass. As a result, the elements in the modern periodic table are arranged in order of increasing atomic number. In this laboratory investigation, you will select the appropriate data and then analyze the information to determine the group and period trends for atomic radius, first ionization energy and electronegativity. Problem: Which properties of elements are repeated periodically? Procedures: Analyze data in tables, charts and/or graphs to describe periodic trends. Prepare charts and/or graphs using the data on the periodic table. Complete the data chart for the following elements. Symbol Atomic Number Number of Protons 19 Li Rb 11 55 Complete the data chart for the elements. Symbol Atomic Number Number of Electrons Ne 8 6 4 F 3 7 B 1|Page Atomic Radius (picometers) 227 152 244 186 262 Atomic Radius (picometers) 70 66 77 112 64 152 71 80 Name ______________________________________________ Chemistry Analyzing Trends in Data – Atomic Radius Date ____________ Period __________ Atomic Radius = half the distance between the nuclei of identical atoms Prepare one graph that includes two data lines. Use a different colored pencil for each graph line. Complete the key for your graph that indicates the category for each data line. Do not forget to label your axis. Atomic Number is the independent variable. Plot the graphs for: Group I - Atomic Radius versus Atomic Number 2|Page KEY Name ______________________________________________ Chemistry Analyzing Trends in Data – Atomic Radius Date ____________ Period __________ KEY Period 2 – Atomic Radius versus Atomic Number Discussion Questions: Your answers for questions 1 & 2 must be in complete sentences. 1. Based on your graph, what is the relationship between atomic number and atomic radius in group 1? Explain this trend using your knowledge of the Bohr atom. 3|Page Name ______________________________________________ Chemistry Analyzing Trends in Data – Atomic Radius Date ____________ Period __________ 2. Based on your graph, what trend do you observe between the atomic number and the atomic radius in period 2? Explain this trend using your knowledge of the Bohr atom. 3. An example of an atom with an atomic radius smaller than that of Sulfur (S) is __________. A. B. C. D. E. 4. Oxygen (O) Chlorine (Cl) Calcium (Ca) Lithium (Li) None of the above Nitrogen has a larger atomic radius than Oxygen. A. True B. False 5. Identify the largest of each pair listed below and explain why that one is larger. A. oxygen or sulfur B. calcium or potassium C. nitrogen or oxygen D. copper or gold 4|Page