Chemistry Reference
In-Depth Information
We will explore several uses for the periodic table in this section, as well
as a number of terms associated with it. This table will be used extensively
throughout the rest of this course and in subsequent chemistry courses.
All the elements in any horizontal row of the periodic table are said to be
in the same
period.
There are seven periods, the first consisting of just two ele-
ments. The second and third periods contain 8 elements each, and the next two
contain 18 elements each. The sixth period has 32 elements (including 14 inner
transition elements numbered 57 through 71, located at the bottom of the table),
and the last period is not yet complete. The periods are conventionally num-
bered with the Arabic numerals 1 through 7 (Figure 1.6).
EXAMPLE 1.8
Which element begins the fourth period of the periodic table? Which element
ends it? How many elements are in that period?
Solution
Potassium (K) begins the period, Krypton (Kr) ends it, and there are 18 ele-
ments in the period.
Practice Problem 1.8
Which element begins the second period of the
periodic table? Which element ends it? How many elements are in that period?
The elements in any vertical column in the periodic table are in the same
group,
or
family.
They have similar chemical properties, which change gradu-
ally from each one to the one below it. In some groups, the elements are very
Classical
Group Numbers:
IA
IIA IIIB IVB VB VIB VIIB
VIII
IB
IIB IIIA IVA VA VIAVIIA
0
Modern
Group Numbers:
1 2 3 4 5 6 7 8 9 10 1112 13 1415161718
Periods
1
H
2
3
4
5
6
7
Coinage
metals
Noble
gases
Halogens
Alkali
metals
(not including
hydrogen)
Alkaline
earth metals
Groups and Periods
Figure 1.6
