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Periodicity and the

Periodic Table Carolina Distance Learning

Investigation Manual

Table of Contents

Overview ......................................................................................................... 4

Objectives ....................................................................................................... 4

Time Requirements ........................................................................................ 4

Background .................................................................................................... 5

Materials .......................................................................................................... 7

Safety ............................................................................................................... 8

Preparation ..................................................................................................... 8

Activity 1: Learning to Organize ................................................................. 9

Activity 2: Organizing the Elements.......................................................... 10

Activity 3: Building the Periodic Table ...................................................... 11

Activity 4: Visualizing the Periodicity ........................................................ 12

Disposal and Cleanup ................................................................................ 12

Materials: Pictures ........................................................................................ 12

Overview

Periodic trends and the formation of the periodic table are studied by organizing three

different sets of cards, deciding how to organize the elements and comparing the

organization system with the arrangements of other students. In addition, the organizing

criteria for the designated systems are compared with those of the modern periodic

table. Finally, elemental data are graphed to identify periodic trends.

Objectives

 Use periodicity, a predictable reoccurring pattern, to organize information

 Make inferences using interpolation and/or extrapolation of an existing data set

 Prepare a visual representation depicting how periodicity is evident in the

periodic table of elements

Time Requirements

Preparation ...............................................................................................................5 minutes

Activity 1: Learning to Organize ............................................................................20 minutes

Activity 2: Organizing the Elements ......................................................................20 minutes

Activity 3: Building the Periodic Table ...................................................................20 minutes

Activity 4: Visualizing the Periodicity .....................................................................60 minutes

Background

Dmitri Mendeleev is often credited with creating the first periodic table of the elements;

however, the organization of the modern periodic table did not begin or end with his

table. In the early 1800s, Jöns Jakob Berzelius made a major discovery that would lead

the way for scientists to examine the possibility of a systematic organization of the

elements. He published a list of atomic weights for elements known to him at that time.

This new information and the properties of the elements prompted scientists to attempt

to organize the elements.

One of the first organizational schemes was designed by Johann Dobereiner. He

noticed a pattern of similar properties among some groups of three elements, which he

called triads. He also saw that the average of the weights of the lightest and heaviest

elements in a triad were equal or close to the weight of the middle element. Among

the known elements, however, Dobereiner was able to find only three working triads,

and he was unable to show how any unknown elements might later fit Into his scheme.

His theory faded, but his idea of patterns among elements endured.

A geology professor, Alexandre Béguyer de Chancourtois, published a list of known

elements in what many consider to be the first periodic table. His table consisted of the

elements ordered by atomic weight wrapped around a cylinder in a spiral. Those

elements on the same vertical line had similar properties. De Chancourtois’s table

focused mainly on physical properties and included some ions and compounds in

addition to elements. His table did not predict any unknown elements and largely was

ignored until the work of Dmitri Mendeleev.

John Newland took a different approach to classifying the elements. After arranging

the elements by atomic weight he saw a repeating pattern in which every eighth

element possessed similar properties. He considered this octet arrangement of elements

to be similar to a musical octave. His idea did not gain much support for quite some

time but was one of the precursors to the work of Mendeleev.

Some historians speculate that Mendeleev set out to organize the elements, realizing

like other chemists of his time that there must be some correlation between their mass

and their properties. To find the key to the pattern, he created his own periodic table

card set, listing all known information about each element on a card and then trying

different ways of arranging the cards. Mendeleev ordered his elements by atomic

weight and then grouped them so that chemical and physical properties were similar

among groups. In arranging the known elements sequentially by atomic weight, he

noticed that some of the elements did not match the physical and chemical

characteristics of the groups into which they fell. He moved these elements to other

groups until the physical and chemical characteristics matched. In doing so, he

created empty spaces in his table. Later, Mendeleev hypothesized that there were

undiscovered elements that would fit into the available spaces and he predicted their

chemical and physical properties. Many of these predictions proved accurate when

the elements were later discovered. Our modern periodic table exists because of this

pioneering work.

Mendeleev’s periodic table is not, however, the same periodic table used by chemists

today. Further discoveries and innovations have led to its expansion and modification.

Especially important discoveries include the noble gases by Lord Rayleigh (John William

Strutt) and William Ramsay, the atomic numbers (the current criterion for organization)

by Henry Moseley and the addition of the actinide and lanthanide series.

The modern periodic table organizes elements in horizontal rows, called periods, in

order of increasing atomic number. As before, elements are also organized in a vertical

column, called a family or group, when they share similar physical or chemical

properties. Elements with similar properties occur predictably as a result of regular

variations in the electronic structures of atoms. Predictable, regular variation, with the

tendency to reoccur at regular intervals, is called periodicity.

Activity Details

This activity requires a lab partner or a lab group to share and compare results. An

important part of science is the scientific discussion that occurs to determine the

meaning of the results or during the development of new theory. It is through this type

of discussion that our understanding of scientific results is improved. This communication

of results and discussion of their meaning will be practiced in this activity.

In Activity 1, use periodicity to arrange a set of colored cards based on their

appearance, and then make inferences about how the next column of cards would

appear. Compare your arrangement to that of a classmate and then make inferences

about cards missing from the classmate’s arrangement.

In Activity 2, use periodicity to arrange a set of element information cards based on

their properties of the elements and then make inferences about the properties of the

next row of cards. Compare your arrangement to that of a classmate and make

inferences about cards missing from the classmate’s arrangement.

In Activity 3, arrange a set of element information cards based on their atomic mass

and number of valence electrons of each element. Generalize periodic trends for

atomic radius, first ionization energy and electronegativity.

In Activity 4, use the data from the element information cards arranged in Activity 3 to

prepare a visual representation (graph, illustration or model) depicting periodic trends

for atomic radius, ionization energy and electronegativity.

Materials

Included in the materials kit:

Card Deck 1

Card Deck 2

Card Deck 3

Needed, but not supplied:

Flat workspace (measuring at least 22 x 26 in.)

Camera (cell phone)

Graphing program, such as Microsoft Excel®

Reorder Information: Replacement supplies for the Periodicity and the Periodic Table

investigation can be ordered from Carolina Biological Supply Company, kit 580322.

Call 1-800-334-5551 to order.

Safety

Read all the instructions for this laboratory activity before beginning. Follow the

instructions closely and observe established laboratory safety practices, including

the use of appropriate personal protective equipment (PPE) described in the Safety

and Procedure sections.

Preparation

1. Read the Procedure.

2. Obtain all materials.

3. Make sure each deck is complete and organized separately:

 Card Deck 1: 25 colorful cards with shapes and numbers

 Card Deck 2: 34 cards with element information but no names or atomic numbers

 Card Deck 3: 34 cards with element information, names and atomic numbers

4. Remove the cover card from Card Deck 1 and randomize the set. Then return the

cover card to the deck and set aside.

5. Repeat the preceding step for Card Deck 2 and Card Deck 3.

6. Clear a flat workspace using a table (or the floor, if necessary). Workspace should

be at least 22 x 26 in.

Activity 1: Learning to Organize

1. Examine all of the cards in Card Deck 1 and note the various characteristics of the

cards.

2. Choose one characteristic and arrange the cards according to the chosen

characteristic. This may involve grouping or ordering, depending on the

characteristic chosen.

3. Record this characteristic in the Observations section.

4. Put the cards back into one pile.

5. Choose another characteristic of the cards and arrange the cards according to the

chosen characteristic. This may involve grouping or ordering, depending on the

characteristic chosen.

6. Record this second characteristic in the Observations section.

7. Arrange the cards in a way that incorporates both characteristics listed in the

Observations section.

8. Observe any trends or patterns associated with the way the cards are organized.

Record these trends or patterns in the Observation section.

9. Photograph the arrangement of Card Set 1 as a record of your work.

10. Without disturbing the arrangement, remove two cards at random. Place these two

cards aside.

11. Photograph the arrangement of Card Set 1 (showing blank space for the missing

cards).

12. Share the photograph with a classmate according to your instructor’s directions.

13. Photograph the two cards set aside in Step 10. Share the photograph with a

classmate according to your instructor’s directions.

14. Gather the cards for Card Deck 1 and put them away.

15. Obtain and open the photograph showing a classmate’s arrangement of Card

Deck 1 and try to determine which cards are missing from his arrangement. Record

this prediction in the Observation section.

16. Obtain and open the photograph showing the same classmate’s missing cards.

Record the features from the missing cards in the Observation Section.

Activity 2: Organizing the Elements

1. Examine all of the cards in Card Deck 2 and become familiar with their similarities

and differences.

2. Remove the card with Atomic Mass = 1 and the card with Atomic Mass = 4. Set

them aside until Step 8.

3. Choose one property on the cards that would allow cards to be placed into groups.

Record this property in the Observations section.

4. Stack cards into groups using the property recorded in the previous step.

5. Choose another property on the cards that would allow cards to be ordered within

each stack. Record this property in the Observations section.

6. Spread each stack of element cards out into an ordered column using the property

recorded in the previous step.

7. Observe any trends or patterns associated with the way the cards are organized.

Record the trends or patterns in the Observations section.

8. Pick up the two cards set aside earlier (in Step 2). Incorporate these two cards into

the arrangement using the patterns or trends observed in the previous step.

9. Photograph the arrangement of Card Set 2 as a record of your work.

10. Without disturbing the arrangement, remove two cards at random. Place these two

cards aside.

11. Photograph the arrangement of Card Set 2 (showing blank space for the missing

cards).

12. Share the photograph with a classmate according to your instructor’s directions.

13. Photograph the two cards set aside in Step 10 and share the photograph with a

classmate according to your instructor’s directions.

14. Gather the cards for Card Deck 2 and put them away.

15. Obtain and open the photograph showing a classmate’s arrangement of Card

Deck 2 and try to determine which cards are missing from this arrangement. Record

this prediction in the Observation section.

16. Obtain and open the photograph showing the same classmate’s missing cards.

Record the features from the missing cards in the Observation Section.

These two cards may not fit neatly into the existing arrangement. Use your best

judgment to determine their placement.

It may be necessary to photograph the right and left halves separately.

Activity 3: Building the Periodic Table

1. Examine all of the cards in Card Deck 3, paying attention to the properties listed.

2. Remove the Hydrogen and Helium cards. Set them aside until Step 7.

3. Stack the cards into eight groups on the basis of their number of valence electrons.

4. Place the stacks in an ordered row so that the elements with one valence electron

are to the left and the elements with eight valence electrons are to the right.

5. Within each of the stacks, arrange the cards from lowest atomic number to highest

atomic number.

6. Spread each stack of element cards out into an ordered column so that the card

with the lowest atomic number is at the top of the column. There should be four rows

and eight columns.

7. Pick up the two cards set aside earlier (in Step 2). Place the Hydrogen card above

the Lithium card (on the top left).

8. Place the Helium card above the Beryllium card (on the top left). Determine which

Helium card properties match those of other cards in this vertical column. Record

the similarities in the Observations section.

9. Place the Helium card above the Neon card (on the top right). Determine which

Helium card properties match those of other cards in this vertical column. Record

the similarities in the Observations section.

10. Observe any trends or patterns associated with the organization of cards and

record them in the Observations section.

11. Photograph the arrangement of Card Deck 3 as a record of your work.

12. Collect Card Deck 3 in order of increasing atomic number for use during Activity 4.

It may be necessary to photograph the right and left halves separately.

Activity 4: Visualizing the Periodicity

1. Use the data from Card Deck 3 to prepare a visual representation (graph, illustration

or model) depicting periodic trends for each of the following:

 Atomic radius

 First ionization energy

 Electronegativity

2. Submit electronic files or photographs of the representations prepared during this

activity according to your instructor’s directions.

Disposal and Cleanup

Organize the cards back into their three sets and place back into the investigation kit.

Materials: Pictures

Card Deck 1 Card Deck 2 Card Deck 3

If you are unsure about what visual representation to create, use a chemistry

textbook (or other resources) for ideas of how others have chosen to illustrate

periodic trends.

580322_Periodicity and the Periodic Table_Q.docx

Periodicity and the Periodic Table

Pre-laboratory Question

1. Give an example of a type of real-world item that is organized or sorted in a specific way.

2. How can items in the previous question be organized?

3. Would you notice if one of the items went missing? Why or why not?

4. How is the modern periodic table organized?

Discussion Questions

Activity 1

1. Are there other ways the cards could be organized? If so, what are they?

2. Use the picture taken in Step 8 to predict the appearance of the next column of colored cards.

3. How did your classmate organize his cards?

4. What patterns are associated with your classmate’s organizational scheme?

5. How did your predicted description of the missing cards compare with the actual missing card?

6. Are there any changes you would make to your organizational system? If so, what changes would you make?

Activity 2

1. Are there other ways the cards could be organized? If so, what are they?

2. Use the picture taken in Step 9 to predict the appearance of the next row of cards.

3. How did your classmate organize his cards?

4. What patterns are associated with your classmate’s organizational scheme?

5. How did you predict the properties of the missing elements?

6. How did your predicted description compare with the actual description?

7. Are there any changes you would make to your organizational system? If so, what changes would you make?

Activity 3

1. Why does the modern periodic table place helium in a family with neon instead of with beryllium?

Atomic Mass

1. Why are the elements no longer organized by atomic mass?

2. What pattern is there with regard to valence electrons, oxygen bonding ratio and electron configuration?

3. Where in the periodic table are the elements with the largest atomic radii? Where are those with the smallest atomic radii?

4. How does atomic radius change from left to right across a period, or row, in the periodic table?

5. How does atomic radius change from top to bottom down a group, family or column in the periodic table?

6. Why does this trend exist in atomic radii?

7. How do the atomic radii of the following elements compare? Which is larger?

a. Se and Br

b. Rb and Cs

c. Ca and As

d. Sn and Pb

Ionization Energy

8. Where in the periodic table are the elements with the greatest first ionization energies? Where are those with the smallest first ionization energies?

9. How does first ionization energy change from left to right across a period, or row, in the periodic table?

10. How does first ionization energy change from top to bottom down a group, family or column in the periodic table?

11. What is the relationship between the trend in ionization energy and the trend in atomic radius? Why does this relationship exist?

12. How does the first ionization energy of the following elements compare? Which is higher?

a. Se and Br

b. Cl and I

c. Ca and As

d. Sr and Rb

Electronegativity

13. Where in the periodic table are the elements with the greatest electronegativity? Where are those with the least electronegativity?

14. How does electronegativity change from left to right across a period, or row, in the periodic table?

15. How does electronegativity change from top to bottom down a group, family or column in the periodic table?

16. How does the electronegativity of the following elements compare? Which is higher?

a. Se and Br

b. Cl and I

c. Ca and As

d. Sr and Rb