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Chemistry

Unit Activity

Unit 2: Periodic Table
This Unit Activity will help you meet these educational goals:
 Science Inquiry—You will explore the contribution of various scientists for
developing the periodic table by doing online research and collecting information
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 STEM—You will get an insight into STEM careers that are uniquely and personally
creative
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Introduction
Since ancient times, people have been aware of basic chemical elements such as gold,
silver, and copper
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About 60 elements were
known by 1860
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The story of the
periodic table provides a good example of how scientific understanding develops over
time through the creativity and work of many individual scientists
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In 1789, Antoine Lavoisier introduced a list of 33 elements grouped
into metals, non-metals, and gases
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However, the major breakthrough came in 1869
in the form of Mendeleev’s periodic table
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This periodic table
was later refined by Mosley and Seaborg
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You will
also arrange elements on the basis of their physical and chemical properties and then
predict trends among them
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You can use
the key search terms to find more information about the scientists who contributed toward the
development of the periodic table
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1
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What were his conclusions?
Type your response here: Newland’s conclusions were that if the elements are arranged
according to increasing atomic weight, elements with similar physical and chemical
properties occur after each interval of eight elements
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2
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First, he mixed metals and non-metals, and his groups contained elements that
weren’t exactly similar in physical and chemical properties
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Another reason is that the
transition metals greatly affected the pattern of the table
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3
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Mendeleev also pointed out that previous atomic weights of some
elements were incorrect, and he also predicted the discovery of new elements and left a
blank space on his table for where they would fit in
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He also pointed out that the elements do not perfectly fit together when
following an increasing atomic mass order
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What were Henry Mosley’s contributions toward the development of the periodic table?
Type your response here: Mosley found a relationship between an element's X-ray
wavelength and its atomic number and reorganized the periodic table by electronic charge
(atomic numbers) rather than atomic weight
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Mosley, like Mendeleev,
also predicted the positions of new elements in his table at numbers 43 and 61
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5
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He did this because during his research working with Americium and Curium, he
found that they could not be properly isolated and that the expected chemical properties of
the new elements were different
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2

Task 2: Arrangement of Elements
1
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You are provided with two sets of
cards that list properties of various elements
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One set of cards lists the names of known
elements and their properties, while the other set of cards lists the properties of a few
unknown elements
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Known Elements Set

K
Physical State: solid
Conductivity: good
Solubility (H2O): reacts
rapidly
o
Melting Point: 64 C

I
Physical State: solid
Conductivity: very poor
Solubility (H2O): negligible
o
Melting Point: 114 C

Ge
Physical State: solid
Conductivity: fair
Solubility (H2O): none
o
Melting Point: 938 C

Ba
Physical State: solid
Conductivity: good
Solubility (H2O): reacts strongly
o
Melting Point: 727 C

Cl
Physical State: gas
Conductivity: poor
Solubility (H2O): slight
o
Melting Point: -102 C

Rb
Physical State: solid
Conductivity: good
Solubility (H2O): reacts violently
o
Melting Point: 39 C

Ca
Physical State: solid
Conductivity: good
Solubility (H2O): reacts
o
Melting Point: 842 C

Si
Physical State: solid
Conductivity: intermediate
Solubility (H2O): none
o
Melting Point: 1414 C

Unknown Elements Set

3

Au
Physical State: solid
Conductivity: excellent
Solubility (H2O): None
o
Melting Point: 1064 C

Ar
Physical State: gas
Conductivity: none
Solubility (H2O): negligible
o
Melting Point: -189 C

Ag
Physical State: solid
Conductivity: excellent
Solubility (H2O): None
o
Melting Point: 962 C

Xe
Physical State: gas
Conductivity: very poor
Solubility (H2O): none
o
Melting Point: -112 C

Element 1
Physical State: gas
Conductivity: very poor
Solubility (H2O): none
o
Melting Point: -157 C

Element 2
Physical State: solid
Conductivity: good
Solubility (H2O): reacts
rapidly
o
Melting Point: 777 C

Element 4
Physical State: gas
Conductivity: very poor
Solubility (H2O): negligible
o
Melting Point: -7 C

Element 3
Physical State: solid
Conductivity: poor
Solubility (H2O): none
o
Melting Point: 327 C

Element 5

Element 6

Physical State: solid
Conductivity: excellent
Solubility (H2O): none
o
Melting Point: 1085 C

Physical State: solid
Conductivity: good
Solubility (H2O): reacts
violently
o
Melting Point: 29 C

a
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Note that we’re using the international group numbers (1-18), followed by the
American scheme for the A-group elements in parentheses
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Now, inspect the properties of the unknown elements, compare them to the
properties of your known elements, and see where the unknown elements best fit
in the table above
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Type your response here:

Write down the names and full electron configurations of the unknown elements
you identified above
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List the elements in the increasing order of their electronegativity
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Type your response here: The element with the least electro negativity on the
list is Cesium
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Copper has the third most electro
negativity, and after is Bromine being the second most electronegative
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My
reasoning for this answer is that the electro negativity trend follows an
increasing role going from left to right on the period table
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3
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Type your response here: Element 6 has the lowest ionization energy
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Element 6, being Cesium has the lowest I
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and this fact
makes sense
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E
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Cesium, located in the bottom left of the
periodic table (where I
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is the lowest), has the lowest I
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compared to
Strontium and Bromine
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__________________________________________________________________________

Resources
history of the periodic table
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Evaluation
5

This project will be evaluated on a rubric that is based on the completeness, clarity, and
thinking you exhibit in the Directions and Analysis section above
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The free response test item accessed below is related to this unit’s concepts and content but
will draw from your prior chemistry knowledge as well
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Download: Free Response Test





Respond to Question 6
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Answer all parts of the question thoughtfully and concisely to the extent of your ability
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For Scoring: Scoring Guidelines
See Question 6

6



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