Periodic Table From the rising of the sun unto the setting of the same, the name of Lord is worthy of praise. Psalm 112:3

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1 Periodic Table From the rising of the sun unto the setting of the same, the name of Lord is worthy of praise. Psalm 112:3 Introduction Dmitri Mendeleev was a Russian scientist credited as the first to publish a version of the Periodic Table that we would recognize today. Tradition has it that he discovered the table by writing all the known elements (56 at the time) and their properties on cards. He then organized the cards in various ways searching for patterns. He noted that when he arranged the elements by their chemical properties, specific properties would repeat regularly. In 1869, Mendeleev presented a Periodic Table to the Russian Chemical Society in which he showed that elements arranged according to both their atomic weight and valence exhibited periodicity of properties. Mendeleev even left spaces for Unknown elements and predicted their properties. These elements were discovered later, and his predictions were proven accurate. Mendeleev s Periodic Law can be summarized as The physical and chemical properties of elements are periodic functions of their atomic masses. In this lab, you will recreate Mendeleev s experiment with placing elements with known properties in Groups. Then, you will identify properties of unknown elements by examining the pattern of known element properties. Learning Objectives: Understand the methodology used by early chemists to organize elements based on properties Materials Required: From Chemistry Kit Mendeleev Cards (found below) Student Supplied Periodic Table Scissors Preparation For this activity you will be given a set of 21 cards: 17 are elements with pretend names and with properties listed 4 are elements with properties you must discover o Labeled UE-1 through UE-4 (UE for Unknown Elements) Your task is to identify some properties of the unknown elements. Remember, elements in the same group tend to show similar physical and chemical characteristics. For example: Group 2A elements have 2 valence electrons and tend to lose both to form ions with a +2 charge. They consistently react with Chlorine (Cl) to form a molecule with the general formula of XCl2. Other properties with periodicity in going from top to bottom in a Group include: increasing Atomic radii; decreasing Electronegativity; increasing Density. Of course, there are exceptions, but in general, these trends will hold Catholic Initiatives in Math and Science, LLC All Rights Reserved 1

2 Experiment 1. Print out the Mendeleev cards (found at the end of this protocol) and cut them apart 2. Arrange the element cards into 7 vertical columns (Groups) and 3 horizontal rows (Periods) as shown below: Group A Group B Group C Group D Group E Group F Group G Period 1 Q D F UE-1 W K T Period 2 J R I X U G B Period 3 Y UE-2 UE-3 C P Z UE-4 3. Atomic Mass Observe: Examine the atomic mass of the elements across the periods That is, how does mass change from Q to T; from J to B; and from Y to Z? Predict: : Based on the trend of atomic masses of the elements in Period 1, assign a mass to UE-1 Based on the trend of atomic masses of the elements in Periods 2 and 3, assign atomic masses to UE-2, UE-3 and UE-4 Your predictions could be exact, such as Mass of 28 Or, your predictions may best be described with a range such as Mass greater than 28 but less than Physical Properties Observe: Examine the physical properties of each Group How does the physical state change in Group A in elements Q to Y; In Group B in elements D to R.and etc., to Group G in elements T to B? In the same way, determine how the melting points change from top to bottom in each of the Groups Predict: Based on the trends of the physical states of elements within a group, predict the physical states of: UE-2 in Group B; UE-3 in Group C; UE-1 in Group D, and; UE- 4 in Group G Based on the trends of the melting points of elements within a group, predict the melting points of: UE-2 in Group B; UE-3 in Group C; UE-1 in Group D, and; UE-4 in Group G UE-4 Your predictions could be exact, such as Melting Point 5 o C Or, your predictions may best be described with either a range, or an open-ended value such as Melting Point >5 o C Catholic Initiatives in Math and Science, LLC All Rights Reserved 2

3 5. Chemical Properties Observe: Examine the chemical properties of each Group How does the reactivity with Hydrogen change in Group A in elements Q to Y; In Group B in elements D to R.and etc., to Group G in elements T to B? In the same way, determine how the reactivity with Chlorine change from top to bottom in each of the Groups Predict: : Based on the trends of the chemical states of elements within a group, predict the reactivity with Hydrogen of: UE-2 in Group B; UE-3 in Group C; UE-1 in Group D, and; UE-4 in Group G Based on the trends of the melting points of elements within a group, predict the reactivity with chlorine of: UE-2 in Group B; UE-3 in Group C; UE-1 in Group D, and; UE-4 in Group G These answers should be exact such as XH2 6. When the cards of the unknowns are complete, answer the questions in the Lab Report 2016 Catholic Initiatives in Math and Science, LLC All Rights Reserved 3

4 Lab Report for: Data Analysis 1. Mendeleev arranged the elements in his Periodic Table in order of increasing mass. Are all of these known elements arranged in order of increasing mass? If not, which one(s) is(are) out of order? 2. In the Periodic Table the elements within a column (or Group) have similar properties. Which property/properties seem(s) most consistent for the elements within the column (Group)? 3. Make a statement about the trend in melting points as you go from top to bottom in the first 3 Groups (Groups A, B and C). 4. Describe your reasoning behind: Assigning physical and chemical properties of UE-1 Assigning physical and chemical properties of UE-2 Assigning physical and chemical properties of UE-3 Assigning physical and chemical properties of UE-4 *Note: You may give it a symbol of your own for ease in making compounds with H and CL Unknown Element-1 (UE-1) Unknown Element-2 (UE-2) Unknown Element-3 (UE-3) Unknown Element-4 (UE-4) 5. Place your prediction answers in the tables found in the Lab Report: 2016 Catholic Initiatives in Math and Science, LLC All Rights Reserved 4

5 Cut out the Mendeleev Cards----- B 40 Monoatomic gas -190 o C None known None known BLANK C D 75 9 Gray solid Steel gray solid 817 o C 1,280 o C CH3 DH2 CCl3 DCl2 Unknown Element 1 (UE-1) G 35 Green-yellow diatomic gas -101 o C None known None known F 12 Soft black solid 3,550 o C FH4 FCl4 Unknown Element 2 (UE-2) B 40 Monoatomic gas -190 o C 937 o C GH 2016 Catholic Initiatives in Math and Science, LLC All Rights Reserved 5

6 GCl I J Lustrous gray solid Soft silvery metallic solid 1,410 o C 98 o C IH4 JH ICl4 JCl K P Pale yellow diatomic gas Solid -220 o C 221 o C KH PH2 KCl PCl2 Q R 7 24 Silvery soft metallic solid Silvery white metallic solid 181 o C 640 o C QH RH2 QCl RCl2 T 20 Monoatomic gas -249 o C None known None known W 16 Diatomic gas -218 o C WH2 or W2H2 WCl2 Unknown Element 3 (UE-3) Unknown Element 4 (UE-4) 2016 Catholic Initiatives in Math and Science, LLC All Rights Reserved 6

7 U X Yellow solid White solid 113 o C 280 o C UH2 XH3 UCL2 or U2CL2 XCl3 or XCl5 Y Z Soft silvery metal Red-brown liquid 64 o C -7 o C YH ZH YCl ZCl 2016 Catholic Initiatives in Math and Science, LLC All Rights Reserved 7