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Alchemy Unit – Investigation II
Lesson 4: Create a Table
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.)
• What do you think the numbers represent?
The Big Question
• How did Mendeleyev organize the elements?
You will be able to:
• Explain how the periodic table of elements is organized.
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.
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.
• 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.
Activity
• One set of elements Mendeleyev grouped together was Magnesium, Calcium and Strontium.
Activity
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
Reaction with acid
Found in
Magnesium Mg
Found in MgCl2 (s)
Calcium Ca
Found in CaCl2 (s)
Strontium Sr
Found in SrCl2 (s)
• Magnesium reacting in air
Activity - magnesium
• Magnesium reacting in acids
Activity - magnesium
• Calcium reacting in air
Activity - calcium
• Calcium reacting in acids
Activity - calcium
• Strontium reacting in air
Activity - strontium
• Strontium reacting in acids
Activity - strontium
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.
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?
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.
(cont.)
• Notice there is a card missing in the middle.
• Notice where hydrogen and helium were placed. Why do you think they were placed in those columns?
• What information should be on this card?… (cont.)
• How do you think Mendeleev knew there was a gap in the middle?
Germanium
Ge 62.7
Germanium
Ge 62.7
Germanium
Ge 66.0
Germanium
Ge 72.6
A B C
D
Germanium
Ge 72.6
(cont.) E
• Below are five possible cards for the missing element we call germanium. Which card seems most accurate to you? What is your reasoning?
• What would you add to the three empty corners to complete the card?
(cont.)
(cont.)
Germanium ? Moderately hard Silvery solid metalloid
? ?
Ge 72.6
Reacts very slowly With oxygen
Found in GeH4 gas
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 CdCl2 (s)
Zinc Zn
Moderately hard silvery solid, metal
Reacts very slowly with water
Found in ZnCl2 (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 HgCl2 (s)
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.