Elements, Atoms, Ions, And The Periodic Table Worksheet With Answers
ADVERTISEMENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14Chapter 3. Elements, Atoms, Ions, and the Periodic Table
The Periodic Law and the Periodic Table
In the early 1800's many elements had been discovered and found to have different
properties. In 1817 Döbreiner's triads –with regularly varying properties: (Mg, Ca, Ba) (F, Cl,
Br) and (S Se Te).1865: Newlands – "law of octaves", about 55
elements: pattern of reactivity follows after 8 elements. However, no
one had found a clear "order" in their properties until Mendeleev,
Dmitri (1834-1907) arranged 63 then known elements in the order of
increasing atomic mass in a periodic table
and showed some
chemical properties would reappear periodically. In certain cases, he
placed a lighter slightly heavier element before a lighter element so
that the chemical properties of the vertical columns would be
preserved. Even though in a different and much less clear form
Meyer, Lothar (1830–1895) also came up with a graph showing
periodic properties similar to Medeleev.
In Mendeleev's table, there was a gap. He purposely left blank position in his table so
that the consistent vertical columns with the same chemical properties would be preserved.
These missing elements were later discovered.
The periodic law is an organized "map" of the elements that relates their structure to
their chemical and physical properties. The periodic table is the result of the periodic law, and
provides the basis for prediction of such properties as relative atomic and ionic size, ionization
energy, and electron affinity, as well as metallic or non-metallic character and reactivity.
The modern periodic table exists in several forms. The most important variation is in
group numbering. The tables in the text use the two most commonly accepted numbering
systems.
Numbering Groups in the Periodic Table
Periods and Groups
Periods are the horizontal rows of elements in the periodic table; the columns represent
groups or families.
Elements in a vertical group have similar chemical properties. The vertical groups are
currently named by numbers ranging from 1 to 18. An older way to identify the vertical groups
is to use a Roman number and the capital letters A or B. Vertical groups of main group
elements (or representative elements) were given a Roman numeral plus the letter A. Vertical
groups of transition elements were given a Roman numeral plus the letter B.
Representative elements are elements that always lose or gain the same number of
electrons in chemical reactions.
Transition elements are elements that can lose or gain variable numbers of electrons in
chemical reactions.
The lanthanide series and the actinide series are parts of periods 6 and 7, respectively, and
groups that have been named include the alkali metals, the alkaline earth metals, the halogens,
and the noble gases. Group A elements are called representative elements; Group B elements
are transition elements. Metals, metalloids, and nonmetals can be identified by their location on
the periodic table.
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education