Chemistry Reference
In-Depth Information
The following shows six Lewis dot diagrams with their elemental sym-
bols replaced by “X”s. Match the Lewis dot notation to the neutral ele-
ment that it could represent for questions 3-8.
X
X
X
X
X
X
A.
B.
C.
D.
E.
F.
3.
Helium
5.
Oxygen
7.
Nitrogen
4.
Lithium
6.
Aluminum
8.
Fluorine
Lesson 3-7: The Periodic Table of Elements
Perhaps the most interesting thing about the Periodic Table of Ele-
ments is how much information is hidden in it. To the untrained eye, the
periodic table appears to only show the elemental symbols, elemental
names, atomic numbers, and atomic masses. However, someone who knows
a bit more chemistry can “squeeze” much more information out of the same
table. You will learn to use the periodic table to check your electron con-
figurations, orbital notations, and Lewis dot notations. You will also learn
to use the periodic table to check many relative properties of the elements,
such as reactivity, electronegativity, and metallic character. All of this in-
formation is there, if you know how to use the table correctly. It is certainly
in your best interest to learn as much about the periodic table as possible,
because you are allowed to make use of it on many exams and quizzes. If
you are able to extract all kinds of information from it, it becomes an in-
credibly useful “cheat sheet,” except that you're allowed to use it!
Let's look at a basic example of the periodic table shown on page 101,
and review what we know already.
Each of the boxes in Figure 3-7a contains two numbers and one or
more letters. The top number in each box is called the atomic mass. The
letter or letters in each box represent the elemental symbol. The bottom
number in each box is called the atomic number.
The atomic number is the number of protons found in the nucleus of an
atom of that particular element. Oxygen, for example, with its atomic num-
ber of eight, is made up of atoms with eight protons in each nucleus. In a
neutral atom, the number of electrons in the electron cloud is equal to the
number of protons in its nucleus.
The elemental symbol for each element is made up of only one capital
letter and, in some cases, one or more lowercase letters. With only twenty-six
letters and more than 100 elements, it is necessary to combine the letters to
