Addendum to Hebden: Chemistry 11
Graphing Data:
ELECTRONEGATIVITY, ATOMIC RADII AND IONIC RADII DATA
The following data table includes information about three atomic properties for elements in the first two and last
six columns (s- and p-blocks) of the periodic table, as well as for the first row of the transition metals.
Electronegativity (EN): There is more than one way to calculate the electronegativity; the values originally
calculated by Linus Pauling are used here. All values are in kJ/mol.
Atomic Radius: The atomic radius of isolated atoms is difficult to measure in a consistent manner. Hence
the table shows the value calculated from sophisticated quantum mechanical mathematics. All values are in
–12
picometers (10 m).
Ionic Radius: The ionic radius differs depending on the crystal in which the ion exists. The values here are
considered to be typical. The charge of the ion formed is indicated in parentheses. Where an atom forms
–12
more than one type of ion, the most stable ion is used. All values are in picometers (10 m).
Element
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Atomic
No.
1
EN
2.20
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
–
0.98
1.57
2.04
2.55
3.04
3.44
3.98
–
0.93
1.31
1.61
1.90
2.19
2.58
3.16
–
0.82
1.00
1.36
1.54
1.63
1.66
1.55
1.83
1.88
Atomic
Radius
53
31
167
112
87
67
56
48
42
38
190
145
118
111
98
88
79
71
243
194
184
176
171
166
161
156
152
Ionic
Radius
–7
8.4 x 10 (+1)
–
0.078 (+1)
0.034 (+2)
0.023 (+3)
0.260 (-4)
– (-3)
0.132 (-2)
0.133 (-1)
–
0.098 (+1)
0.078 (+2)
0.057 (+3)
0.026 (+4)
0.212 (-3)
0.184 (-2)
0.181 (-1)
–
0.133 (+1)
0.106 (+2)
0.083 (+3)
– (+4)
0.061 (+4)
0.064 (+3)
0.091 (+2)
0.082 (+3)
0.082 (+2)
Element
Atomic
No.
EN
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Rb
Sr
In
Sn
Sb
Te
I
Xe
Cs
Ba
Tl
Pb
Bi
Po
At
Rn
Fr
Ra
28
29
30
31
32
33
34
35
36
37
38
49
50
51
52
53
54
55
56
81
82
83
84
85
86
87
88
1.91
1.90
1.65
1.81
2.01
2.18
2.55
2.96
3.00
0.82
0.95
1.78
1.96
2.05
2.1
2.66
2.6
0.79
0.89
1.62
2.33
2.02
2.0
2.2
2.4
0.7
0.9
Atomic
Radius
149
145
142
136
125
114
103
94
88
265
219
156
145
133
123
115
108
298
253
156
154
143
135
127
120
–
–
Ionic
Radius
0.078 (+2)
0.072 (+2)
0.083 (+2)
0.062 (+3)
0.272 (-4)
0.069 (+3)
0.191 (-2)
0.196 (-1)
–
0.149 (+1)
0.127 (+2)
0.092 (+3)
0.093 (+2)
0.089 (+3)
0.211 (-2)
0.220 (-1)
–
0.165 (+1)
0.143 (+2)
0.105 (+3)
0.132 (+2)
0.096 (+3)
0.230 (-2)
–
–
0.189 (+1)
0.152 (+2)
Hebden: Electronegativity, Atomic Radii and Ionic Radii Data – 2
EXERCISES:
1. Recall that neutral atoms consist of two or more elementary particles. Suggest a reason why the ionic
+
radius of H is so much smaller than the ionic radius of the other atoms in the table.
2. Plot the electronegativity versus atomic number for the first 38 elements on the following graph and
connect each point to the next with a straight line. Where no data exists, leave a blank space and do not
connect the point before the blank to the point after the blank.
4.0
3.5
3.0
2.5
Electronegativity
2.0
1.5
1.0
0.5
0
5
10
15
20
25
30
35
40
Atomic Number
3. Plot the atomic radius versus atomic number for the first 38 elements on the following graph and connect
each point to the next with a straight line.
300
250
200
Atomic Radius
(pm)
150
100
50
0
0
5
10
15
20
Atomic Number
25
30
35
40
Hebden: Electronegativity, Atomic Radii and Ionic Radii Data – 3
4. Plot ionic radius versus atomic number for:
(a) the alkali metals,
(b) the alkaline earth metals, and
(c) the halogens,
using the following graphs and connect each point to the next with a straight line.
0.20
0.15
Ionic 0.15
Radius
(pm)
Ionic 0.10
Radius
(pm)
0.10
0.05
3 11 19 37 55 87
4 12 20 38 56 88
Atomic Number
Atomic Number
0.20
Ionic 0.15
Radius
(pm)
0.10
9 17 35 53
Atomic Number
5. Write a statement that summarizes the trend in electronegativity:
nd
(a) going from left to right across the 2 period (Li, B, etc.) of the periodic table, and
st
(b) going down the 1 column of the periodic table,
6. Write a statement that summarizes the trend in atomic radius:
rd
(a) going from left to right across the 3 period of the periodic table, and
(b) going down the column containing the halogens.
7. Write a statement that summarizes the trend in ionic radius going down the column containing the alkaline
earth metals.
8. Examine the trend in ionic radius for each of:
(a) Li, Be and B,
(b) Na, Mg and Al, and
(c) K, Ca and Ga.
Write a statement that summarizes the trend in ionic radius as the ionic charge increases.