Periodic Law Graphing Activity
Name _________________________________
Date _________________ Period __________
A) Atomic Radius
1. Atomic radius is measured in a unit called angstroms, Å. Define atomic radius.
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2. The atomic radii of the elements from Group 1 are Li, 1.52 Å; Na, 1.86 Å; K, 2.27 Å;
Rb, 2.48 Å; Cs, 2.66 Å. Plot these radii on the graph below.
Atomic Radius (Å)
3.0
2.0
1.0
Li
Na
K
Rb
Cs
Group 1 (IA) Elements (Increasing Atomic Number →)
3. Trend: Down a group, as atomic number increases, atomic radius ____________________.
4. Explain the trend:
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5. The atomic radii of the elements from Period 3 are Na, 1.86 Å; Mg, 1.60 Å; Al, 1.43 Å;
Si, 1.17 Å; P, 1.10 Å; S, 1.04 Å; Cl, 0.99 Å. Plot these radii on the graph below.
Atomic Radius (Å)
2.0
1.5
1.0
0.5
Na
Mg
Al
Si
P
S
Cl
Period 3 Elements (Increasing Atomic Number →)
1
6. Trend: Across a period, as atomic number increases, atomic radius_____________________.
7. Explain this trend:
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B) Ionization Energy
8. Define first ionization energy.
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9. What are second, third, and other successive ionization energies?
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First Ionization Energy (kJ/mol)
10. The first ionization energies for the elements in Group 2 are Be, 900 kJ/mol; Mg, 738 kJ/mol;
Ca, 590 kJ/mol; Sr, 550 kJ/mol; Ba, 503 kJ/mol. Plot these energies on the graph below.
1000
750
500
Be
Mg
Ca
Sr
Ba
Group 2 (IIA) Elements (Increasing Atomic Number →)
11. Trend: Down a group, as atomic number increases, 1st ionization energy ________________.
12. Explain this trend:
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2
First Ionization Energy (kJ/mol)
13. The first ionization energies for the elements in Period 2 are Li, 520 kJ/mol; Be, 900 kJ/mol;
B, 801 kJ/mol; C, 1087 kJ/mol; N, 1402 kJ/mol; O, 1314 kJ/mol; F, 1681 kJ/mol.
Plot these energies on the graph below.
1500
1000
500
Li
Be
B
C
N
O
F
Period 3 Elements (Increasing Atomic Number →)
14. Trend: Across a period, as atomic number increases, 1st ionization energy _______________.
15. Explain this trend and any irregularities:
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C) Electronegativity
16. Define electronegativity.
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3
17. The electronegativity values for elements in Group 2 are Be 1.50; Mg, 1.29; Ca, 1.02; Sr, 0.97;
Ba, 0.93. Plot these electronegativities on the graph below.
Electronegativity
1.50
1.25
1.00
Be
Mg
Ca
Sr
Ba
Group 2 (IIA) Elements (Increasing Atomic Number →)
18. Trend: Down a group, as atomic number increases, electronegativity___________________.
19. Explain this trend:
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20. The electronegativity values for elements in Period 2 are Li, 0.96; Be, 1.50; B, 2.02; C, 2.56;
N, 2.81; O, 3.37; F, 4.00. Plot these electronegativities on the graph below.
Electronegativity
4.0
3.0
2.0
1.0
Li
Be
B
C
N
O
F
Period 2 Elements (Increasing Atomic Number →)
21. Trend: Across a period, as atomic number increases, electronegativity___________________.
22. Explain this trend:
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4