Name____________________________________
Block_________
GRAPHING PERIODIC TRENDS
Objective: To use the periodic table to identify trends in ionization energy, electronegativity, and the relative size of atoms.
PRE-LAB DISCUSSION:
The Periodic Table is arranged according to the Periodic Law. The Periodic Law states that when elements are
arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern.
These patterns can be discovered by examining the changes in properties of elements on the Periodic Table. The
properties that will be examined in this lesson are: atomic radius (size), Ionization Energy and Electronegativity.
PURPOSE:
To understand periodic trends relating to atomic radius (size), ionization energy, and electronegativity.
PROCEDURE:
Use the information in these tables to complete the graph as described below.
RESULTS:
Symbol
H
Li
Na
K
Rb
Cs
Symbol
Na
Mg
Al
Si
P
S
Cl
Ar
Atomic Radius
(Picometers)
31
128
166
203
220
244
First Ionization
(kilojoules/mole)
1312
520
496
410
403
376
Electronegativity
(4-point scale)
2.1
1.0
0.9
0.8
0.8
0.7
Atomic Radius
(Picometers)
166
141
121
111
107
105
102
106
First Ionization
( kilojoules/mole )
496
738
578
787
1012
1000
1251
1521
Electronegativity
(4-point scale)
0.9
1.2
1.5
1.8
2.1
2.5
3.0
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1. Define each of these terms: Atomic radius, First Ionization Energy, and Electronegativity.
Atomic radius:
Ionization Energy:
Electronegativity:
2. Using colored pencil or pen, list under the symbol (in this order!) the Atomic Radius, First Ionization Energy, and
Electronegativity. Use a different color for each property. Example: Write all of the Atomic radius values in red,
all of the First ionization energies in green, and all of the Electronegativities in blue.
Of course, you can pick any colors that are available, as long as you are consistent.
3. Observe the trends in each property as you go down the Family (group), and as you go across the
Period.
4. Complete each statement with the observed trend (increase or decrease).
Periodic Trends
H
Across a period (→) atomic radius tends to
Across a period (→) first ionization energy tends to
Li
Across a period (→) electronegativity tends to
Na
Mg
Al
Si
P
K
Down a Group (↓) atomic radius tends to
Rb
Down a Group (↓) first ionization energy tends to
Down a Group (↓) electronegativity tends to
Cs
S
Cl
Ar
1. Arrange the following atoms in order from lowest to highest ionization energy.
A) Ca, Se, As, Br
B) As, N, P, Bi
C) Ga, Al, S, Si
D) Li, K, O, C
E) Te, O, S, Po
F) In, Te, Sn, I
2. Order the following elements from smallest to largest in atomic radii (size).
A) Al, Na, S, Mg
B) C, Sn, Pb, Si
C) K, Se, Ca, Br
D) Be, Ca, C, B, Mg
E) Ga, Al, Cl, P
F) O, Se, S, Ne