Class set Mendeleev’s Periodic Table Background Dmitri Mendeleev was a Russian scientist who is widely recognized as the chemist who arranged the Periodic Table with the elements in the order of atomic weight. He observed that when arranged this way there was a “periodicity” of recurring similar properties. Other scientists were working on this same task at the time, but Mendeleev was the only one who left spaces in his table and predicted that new elements would be discovered that had the properties that matched the blanks. Mendeleev wrote everything known about the 60 elements that existed at that time on cards, and used those cards to arrange the elements by atomic weight and properties. Objective In this activity, you will use your knowledge of Periodic Trends to identify unknown elements and place them correctly in the Periodic Table. Materials • Mendeleev Periodic Table Cards • Scissors Procedure 1. Cut out the element cards – there are 34 total cards that represent the main block elements (Groups 1, 2, 13-18) in the first five periods. 2. Arrange the cards that include the element’s name as they are arranged on the Periodic Table. There will be 10 blank spaces when you have completed this step. 3. Review the properties listed on the unknown cards and place the cards in the proper place using what you know about periodic trends and metallic properties. 4. When you have finished fill complete the conclusion section below. American Association of Chemistry Teachers |1-263 1 Mendeleev’s Periodic Table Name ____________________ Period _______________ Pre lab (complete before lab) Define the following words: 1. group (with respect to the periodic table) 2. period (with respect to the periodic table) 3. malleable 4. conductive 5. electronegativity 6. ionization energy 7. Complete the table to complete the sentence Gases and the liquid Solids tend to have… tend to have… Melting points that are: Density that is: Conductivity that is: A place on the periodic table that is (left/right/top/bottom) Conclusion (to be completed after lab) Write the identity of the unknown elements in the table below. Unknown Element Name Period Group 1 2 3 4 5 6 7 8 9 10 American Association of Chemistry Teachers |1-263 2 Use the element cards as they are arranged to fill in the table below Describe the trend for each property across Describe the trend for each property down a period for a group for Physical state Physical state down group 17 Conductivity Melting point Melting point Reactivity Electronegativity Electronegativity Ionization Energy Ionization Energy American Association of Chemistry Teachers |1-263 3 .