Alchemy Unit Investigation II. Lesson 4: Create a Table

Transcription

1 Alchemy Unit Investigation II Lesson 4: Create a Table

2 ChemCatalyst In 1889 a Russian chemistry teacher, Dmitri Mendeleev, created an organized table of the elements. At the time only 63 different elements were known. On the next slide, you will see a reproduction of that table. (cont.)

3 What do you think the numbers represent?

4 The Big Question How did Mendeleyev organize the elements?

5 You will be able to: Explain how the periodic table of elements is organized.

6 Activity Purpose: The goal of this lesson is to acquaint you with Mendeleev s organization of the elements by allowing you to create your own table from the patterns you see in the elements.

7 Activity Examine the cards. Describe five different ways you can sort and organize the cards into groups. What are three ways you can arrange your 33 cards in order.

8 Activity Dimitri Mendeleev is credited with organizing the elements into the first periodic table. Mendeleev grouped the elements by reactivity and arranged the elements according to a number that describes the relative weight of each element called the atomic weight.

9 Activity One set of elements Mendeleyev grouped together was Magnesium, Calcium and Strontium.

10 Activity One group of elements that Mendeleyev put into the same group on the periodic table was magnesium, calcium and strontium. Copy the table and fill out the table below. Element Description Reaction with air Magnesium Mg Calcium Ca Strontium Sr Reaction with acid Found in Found in MgCl 2 (s) Found in CaCl 2 (s) Found in SrCl 2 (s)

11 Activity - magnesium Magnesium reacting in air

12 Activity - magnesium Magnesium reacting in acids

13 Activity - calcium Calcium reacting in air

14 Activity - calcium Calcium reacting in acids

15 Activity - strontium Strontium reacting in air

16 Activity - strontium Strontium reacting in acids

17 Activity Although you don t have other metals to compare your observations with, the chemical behavior of these metals are unlike many other metals. Locate the cards of these three elements and then arrange the other 30 cards around them.

18 Activity Stack the cards in order of increasing atomic weight (the number on the card) What is the lightest element in your deck? The heaviest? Begin laying the cards out in a row until you get to magnesium. What element has similar properties to Magnesium?

19 Activity Mendeleev placed the elements with similar properties in the same column. Which column does magnesium fit the best? Pick up the card for sodium? What element card does it resemble? Place it under that card. Continue until you have all the cards laid out.

20 (cont.) Notice where hydrogen and helium were placed. Why do you think they were placed in those columns? Notice there is a card missing in the middle.

21 What information should be on this card? (cont.) How do you think Mendeleev knew there was a gap in the middle?

22 Below are five possible cards for the missing element we call germanium. Which card seems most accurate to you? What is your reasoning? Germanium Germanium Germanium Ge 62.7 Ge 62.7 Ge 66.0 A B C Germanium Germanium D Ge 72.6 E Ge 72.6 (cont.)

23 (cont.) What would you add to the three empty corners to complete the card? Moderately hard Germanium Silvery solid? metalloid Ge 72.6? Found in? Reacts very slowly With oxygen GeH 4 gas (cont.)

24 Check-In Which of the following elements would you find in the same group on the periodic table? Explain your thinking. Cadmium Cd Moderately soft, silvery solid, metal React very slowly with water Found in CdCl 2 (s) Zinc Zn Moderately hard silvery solid, metal Reacts very slowly with water Found in ZnCl 2 (s) Iodine I Bluish black solid, nonmetal Reacts slowly with metals Found in ICl (s) Mercury Hg Silvery liquid, metal Does not react with water Found in HgCl 2 (s)

25 Wrap-Up Mendeleyev organized the periodic table based on the properties of the elements. Mendeleyev s arrangement of the elements helped to predict the existence of undiscovered elements.