CHEMISTRY/EXERCISE
A GRAPHIC ILLUSTRATION OF THE PERIODIC LAW
Name_____________________________
Period_____
In 1912 Moseley summarized the properties of the elements with relation to their atomic number in a law which states,
the properties of the elements are a periodic function of their atomic numbers.
In this exercise we shall study the relationship between the atomic numbers of the elements and some of their physical
properties. To do this we will compare, by means of graphs, the boiling points, ionization energy, and the atomic
radius of the elements in the nitrogen oxygen, halogen, inert gas, hydrogen, and alkali-metal families. Note: Hydrogen
is a single membered family. The pertinent data are given in the table as follows: (1) electronegativity vs. atomic
number, (2) ionization energy vs. atomic number, (3) atomic radius vs. atomic number. Plot atomic number along the
horizontal axis in each case. Number consecutively between 1 & 19, space two, number 33-37, space two, then number
51-55.
Circle each point and label it with the symbol of each element.
Connect the points representing consecutive elements by a solid line in pencil and use a broken line to complete the
graph.
Connect the elements of the same family with solid lines, each in a different color.
ELEMENT
H
He
Li
N
O
F
Ne
Na
P
S
Cl
Ar
K
As
Se
Br
Kr
Rb
Sb
Te
I
Xe
Cs
ATOMIC NUMBER
ELECTRONEGATIVITY
1
2
3
7
8
9
10
11
15
16
17
18
19
33
34
35
36
37
51
52
53
54
55
2.20
0.98
3.04
3.44
3.98
0.93
2.19
2.58
3.16
0.82
2.18
2.55
2.96
0.82
2.05
2.1
2.66
0.79
IONIZATION
ENERGY,
ELECTRON VOLTS
13.6
24.6
5.4
14.5
13.6
17.4
23.6
5.1
11.0
10.4
13.0
15.8
4.3
10.5
9.8
11.8
14.0
4.2
8.6
9.0
10.4
12.1
3.9
ATOMIC RADIUS,
ANGSTROMS, Å
0.37
0.8
1.23
0.74
0.74
0.72
1.1
1.57
1.10
1.04
0.99
1.5
2.03
1.21
1.17
1.14
1.7
2.16
1.41
1.37
1.33
1.9
2.35