Chemistry Reference
In-Depth Information
EXAMPLE 1.13
Use the periodic table to identify each of the following:
(a)
The fifth element of the first transition series
(b)
The element of the fourth period that is also in group VB
(c)
The last lanthanide
(d)
The seventh transition element
(e)
The second actinide metal
(f )
The first element of group VIII
(g) The third halogen
(h)
The first alkaline earth metal
(i)
The first coinage metal
Solution
(a)
Mn
(b) V
(c)
Lu
(d) Co
(e)
Pa
(f )
Fe
(g)
Br
(h) Be
(i)
Cu
Practice Problem 1.13
Identify the second noble gas.
Snapshot Review
❒
The elements are classified in the periodic table for much the same
reasons that matter is classified as described in Section 1.1.
❒
Elements in the same periodic group have similar chemical
properties.
❒
Learn the nomenclature of the table. For example, when the
instructor states that “main group elements are easiest to
understand,” we must know which elements are in the main
groups.
A. What are the atomic numbers (the integers) of the third transition series of
elements?
B. What element that is not naturally occurring has the smallest atomic
number?
1.6
Laws, Hypotheses, and Theories
So many facts are available to scientists as they do experiments and observe
natural phenomena that the data must be classified so that they can be learned
and understood. When a large group of scientific observations is generalized
into a single statement, that statement is called a
law.
For example, when a pen
drops, it falls downward. When a ball drops, it falls downward. These and mil-
lions of other such observations are grouped together and generalized as the law
of gravity. A law is a general statement about observable facts.
After organizing observed data into a law, scientists try to explain the law.
A statement that attempts to explain why a law is true is called a
hypothesis.
If the hypothesis becomes generally accepted, it becomes a
theory.
Einstein
explained the law of gravity with his theory of relativity. Laws and theories are
