Predicting "Missing Elements" Periodic Table (Mel Malhi)

Title: Find The Missing Elements

Principle(s) Investigated: Element relationships, characteristics, periodic table patterns, Periodicity, predicting properties, groups, families, series, periods.

Standards :

Materials: Paint Color sample chips, phone or computer to upload images of your predicted tables

Objective: Arrange your elements "color chips" by having the darker colors (of each group/families of colors) represent larger atomic mass and predict spots to leave for "missing or undiscovered" elements just as Mendeleev predicted.

Procedure: Mendeleev arranged the original periodic table elements by their observed properties. Students will try the same process as Mendeleev did to predict what paint color cards go where in a logical manner.

The basic color of the paint cards represents the chemical properties of the given element card. For example, all the purple cards will have similar chemical properties amongst each other but will differ from the red shades of paint sample cards.

Furthermore, the shade of the paint color represents the elements "Atomic Mass".

So the darker the card color the more atomic mass it has. For example, the light blue card will have less atomic mass than its dark blue cousin but they will share similar chemical properties.

Step 1: ARRANGE the colors in the sequence as seen in the Visible Spectrum R-O-Y-G-B-V across the table from left to right.

• Arrange all the color cards with similar colors in the same column or family going vertically down the table.
• Place the reddist cards to the left and gradually move across the table to end up with the Violet cards to the right. This represents the change from Metallic to NonMetals as seen in the Periodic Table of today.
• Place all the color cards with the same shades (color intensity) in the same rows (periods) which run horizontally across the table from left to right.

Step 2: PREDICT which three color chips "elements" are missing from your arrangement and leave three spaces.

Step 3: TAKE A PICTURE of your periodic table arrangement with the three spaces showing for your missing elements and upload to Dropbox.

Student prior knowledge: Pattern recognition, Elements, atomic mass, characteristics and properties, element groups and families.

Questions & Answers:

1. Explain how you arranged your color chips "elements" on your theoretical periodic table?

2. Did you correctly predict the three missing (undiscovered) elements just as Mendeleev did?

3. Why do you think Mendeleev left spaces for the missing elements that were discovered 15 years later?

Applications to Everyday Life: Predicting the properties of unknown elements- Chemists today still predict the properties of elements today just as Mendeleev did long ago.

Once students understand that elements in the same family share similar properties, they will begin to predict what will go on when an element from one family reacts with an element from another family. This is especially useful in instances where one would want to avoid an interaction between two elements such as a reaction between the elements in Group 1- Li, Na, K, Rb, Cs and Fr with water. These reactions are highly reactive and should be handled with high caution.

Photographs:

Videos:

Additional (very cool) information: Dmitri Mendeleev was born at Tobolsk, Siberia in 1834 and died in 1907. Mendeleev studied science at St. Petersburg and graduated in 1856. In 1863 Mendeleev was appointed to a professorship and in 1866 he succeeded to the Chair in the University. Mendeleev is best known for his work on the periodic table; arranging the 63 known elements into a Periodic Table based on atomic mass, which he published in Principles of Chemistry in 1869. His first Periodic Table was compiled on the basis of arranging the elements in ascending order of atomic weight and grouping them by similarity of properties. He predicted the existence and properties of new elements and pointed out accepted atomic weights that were in error. This organization surpassed attempts at classification by Beguyer de Chancourtois and Newlands and was published a year before the work of Lothar Meyer.

Mendeleev provided for variance from strict atomic weight order, left space for new elements, and predicted three yet-to-be-discovered elements including eke-silicon and eke-boron. His table did not include any of the Noble Gases, however, which had not yet been discovered. The original table has been modified and corrected several times, notably by Moseley, but it had accommodated the discovery of isotopes, rare gases, etc.

Mendeleev anticipated Andrews' concept (1869) of the critical temperature of gases. He also investigated the thermal expansion of liquids, and studied the nature and origin of petroleum. He was considered one of the greatest teachers of his time. In 1890 he resigned his professorship and in 1893 became director of the bureau of weights and measures in St. Petersburg, where he remained until his death in 1907. (http://www.chemistry.co.nz/mendeleev.htm)