CH-01
Rev. 0
Page 12
THE PERIODIC TABLE
DOE-HDBK-1015/1-93
Fundamentals of Chemistry
THE PERIODIC TABLE
All known elements fall into a pattern when placed in a periodic table, and
the position in this pattern is decided by the element's atomic number. This
chapter will discuss the significance of this fact.
EO 1.4
DEFINE the following subdivisions of the periodic table:
a.
Periods of the periodic table
b.
Groups of the periodic table
c.
Classes of the periodic table
EO 1.5
Given a periodic table, IDENTIFY the
following subdivisions:
a.
Periods of the periodic table
b.
Groups of the periodic table
c.
Classes of the periodic table
EO 1.6
LIST the characteristics that elements in the
same group on the periodic table share.
EO 1.7
DEFINE the term valence.
Periodic Table
Over many years of chemical investigation, scientists have discovered a remarkable feature
of the elements. If the elements are arranged in the order of their atomic numbers, the
chemical properties of the elements are repeated somewhat regularly. To a lesser extent, the
physical properties are also repeated periodically. This periodic repetition can be seen in
Table 3. Compare the properties of lithium (Li), sodium (Na), and potassium (K), and also
those of beryllium (Be), magnesium (Mg), and calcium (Ca). In the list of elements shown
in Table 3 the properties are repeated every eighth element.
TABLE 3
Description of the Properties of the First Twenty Elements
Element
Symbol
Atomic
Atomic
Description of Properties
Number
Weight
Hydrogen
H
1
1.008
Colorless gas, reacts readily with oxygen to form H O;
2
forms HCl with chlorine.
Helium
He
2
4.003
Colorless gas, very non-reactive chemically.
