- Why do scientists and chemists use the Periodic Law?
The Periodic Law is is used by Scientists and Chemists
all over the world to arrange the physical and chemical information about the
chemical elements in a systematic way.
Periodic Law -
What is the Definition of the Periodic Law?
The periodic law is the principle that certain
properties of elements occur periodically when arranged by atomic
Periodic Law - Origins and Modern
Periodic Law Origin
- What was the origin of the Periodic Law?
In 1869 the
Russian chemist called Dimitri Mendeleev perceived a
totally new classification method of elements which he called "the periodic table". In
the same year the German scientist, Lothar Meyer, independently
suggested the same ideas. This arrangement brought to light a
great generalization, now known as the Periodic Law. Dimitri Mendeleev
included all the 65 elements
known in his era by their atomic weights and chemical valency.
Such regularities very much simplify the study of chemistry. A
thorough study of one element of a group of elements makes the
study of the other group members a much easier task, since so
many of the properties and chemical reactions of the elements
Dimitri Mendeleev (1834-1907)
who developed the Periodic Law
Periodic Law Origin
- Henry Moseley modifies the Periodic Law
In 1913 the English scientist, Henry Moseley (1887-1915), determined the
atomic number of each of the elements and modified the 'Periodic Law'
accordingly. Moseley realised that when atoms were arranged according to
increasing atomic number, the few problems with the periodic
table which had been developed by Dimitri Mendeleev disappeared.
Because of Henry Moseley's work, the modern periodic table is
based on the atomic numbers of the elements.
Henry Moseley (1887-1915) who modified the Periodic Law
What is an Atomic
The Periodic Law states that the
Physical and Chemical
of the elements recur
way when the elements are arranged in order of increasing
atomic number. The
Periodic Table is therefore arranged
in order of increasing atomic numbers
according to the Periodic Law following the modification by
Henry Moseley. The Periodic Law can be explained further by
comparing the chemical and physical properties of elements.
Table and the Periodic Law corrects errors
The physical constants of many of the elements did not at first
agree with those demanded by the periodic law, and a further
study of many such cases showed that errors had been made. The
Periodic Law has therefore done much service in indicating probable
Periodic Law -
Modern applications of the Periodic Law
When the periodic law was first formulated
when Dimitri Mendeleev developed his theory there were a number
of vacant places in the table which evidently belonged to
elements at that time unknown. From their position in the table, Dimitri Mendeleev predicted, with great precision,
the properties of the elements which he felt sure would one day
be discovered to fill these places. There are still some vacant places in the table,
especially among the heavier elements. The Periodic Law allows
modern scientists to include newly discovered elements in the
Periodic Law - The
Process of developing a Scientific Theory
The following flowchart illustrates the process
of developing a
scientific theory. This process is followed by all scientists
and chemists including Dimitri Mendeleev and Henry Mosely who
formulated the Periodic Law.