Download reviewing key trends

Chemistry 20 – Atoms & Elements
HMWK
2-9
– Periodic Trends
References:
Section 14-3 (Periods of Elements)
Section 14-4 (Groups of Elements)
Section 14-6 (Ionization Energy and Periodicity)
Section 14-9 (Atomic Radius and Periodicity)
Section 14-10 (Ionic Radius)
Smartboard Notes 2-9 Periodic Trends
Groups and Periods
1.
2.
3.
4.
Complete the table on the back side of this sheet, labeled “Families of Elements.”
Where are the lanthanoids located, and how are they similar?
Where are the actinoids, and how are they similar?
What is a similarity between alkali metals and alkaline earth metals?
Ionization Energy
5. What is the difference between a substance’s first ionization energy and the second
ionization energy?
6. Use Figure 14-13 to assist with these:
a) How do the values for the first, second, and third ionization energies compare for
the element ‘oxygen’?
b) Are there any elements that don’t follow the trend you noticed in part a)?
c) Explain how the shielding effect may explain why the trend is this way.
7. Using the graph on the attached sheet labeled “Periodicity of Ionization Energy”:
a) Circle the points that correspond to the peaks of the ionization energy on the graph,
and write the symbol for the element at each peak.
b) Put squares around each point corresponding to the lowest points (“troughs”) of
ionization energy and write the symbol for the element at each trough.
c) What group of elements corresponds to the peaks of ionization energy on your
graph? Which group number is this?
d) Which group of elements occupies the troughs on your graph of ionization energy?
e) What is the trend in the ionization energies as the atomic number increases within a
group of elements (from top to bottom)?
f) What is the trend in the ionization energies as the atomic number increases across a
period of elements (from left to right)?
g) Using your graph, predict a first ionization energy for Cesium.
Radius
8. What are the three types of atomic radius? Give a sentence to show how each is unique.
9. Using the graph on the attached sheet labeled “Periodicity of Atomic Radius”:
a) Circle the points corresponding to the peaks on the graph. Write the symbol for the
element at each peak.
b) Put a square around the points corresponding to the troughs on the graph. Write the
symbol for the element at each trough.
c) What is the group name for the elements found at the peaks of your graph? What
group number is this?
d) What is the group name for the lements found at the
troughs of your graph?
e) What is the trend in the size of atomic radii as the
atomic number increases within a group?
f) What is the trend in the atomic radii as the atomic
number increases across a period or row? What is
the exception to this trend?
g) Estimate the atomic radius for Cesium.
h) Connection to Ionization Energy: how do the peaks
and troughs compare between the ‘Ionization
Energy’ graph and the ‘Atomic Radius’ graph?
Suggest a reason for this.
10. Explain why the radius of a positive ion of an element is smaller than the same element’s
atom, and why the radius of a negative ion is larger than the atom.
Summary
11. Using Figure 14-21 as a guide, first number the groups, and then summarize the periodic
trends across a period (from left to right) and down a group (top to bottom).
Families of Elements:
Your Legend:
Instructions:
1) Write the group numbers above the periodic table above.
2) Identify the following families on your table, and include a legend:
• Oxygen family
• Alkali metals
• Nitrogen family
• Halogens
• Alkaline earth metals
• Noble gases
• Transition metals
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Atomic Radii
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Periodicity of Atomic Radius
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Periodicity of Ionization Energy
First Ionization Energies
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