CO1g8.ppt

Science Teacher 1
Milagros L. Fernandez
Periodic Table
of
DEVELOPMENT

OBJECTIVES:
1. Identify the contributors in the
development of periodic table.
2. Compare the valuable
contributions of Dobereiner, De
Chancourtois, Newlands, Meyer,
Mendeleev and Moseley.
3. Recognize the importance of their
contributions.

1.Who is your favorite
scientist/chemist?
2.What is his/her
contribution?
3.Why did you admire
him/her?

Who do you think are the
scientists who contributed
to the development of the
periodic table of
elements?

TASK:
1.Divide the class into five groups and
assign a leader. Give each group their
different task. Let them choose their
group they want to belong and do the
task according to the HISTORY OF
PERIODIC TABLE OF ELEMENTS.
2.Distribute the handouts and give at
least 6 minutes before the presentation.

TASK 1: MUSIC/JINGLE
TASK 2: SPOKEN POETRY/ POEM
TASK 3: COMIC STRIP
TASK 4: ROLE PLAY PRESENTATION
TASK 5: HOSTING/FAMILY FEUD
HISTORY OF PERIODIC TABLE OF ELEMENTS

TASK RUBRIC:
CONTENT 50%
CREATIVITY 20%
PRESENTATION 20%
COOPERATION 5 %
OVER ALL
IMPACT/OTHERS
5 %
TOTAL 100%

Antoine Lavoiser- 1789
He developed the modern
system of naming chemical
substances and has been
called the “FATHER OF
MODERN CHEMISTRY” for his
emphasis on careful
experimentation
Group elements according to
their properties as metals,
earths, nonmetals, and gases

A. Metallic Character
Metals
Nonmetals
Metalloids
Organization of Elements

B. Blocks
Main Group Elements
Transition Metals
Inner Transition Metals

Johann Wolfgang Dobereiner- 1829
discovered the existence of
families of elements with
similar chemical properties.
Because there always seemed
to be three elements in these
families, he called them
triads. Each of the vertical
columns in Table 7.1
represents one of these
triads.

Alexandre-Émile Béguyer de
Chancourtois-1862
He was the first scientist to
see the periodicity of
elements when they were
arranged in order of their
atomic weights. ( “telluric
screw”) He saw that the
similar elements occurred at
regular atomic weight
intervals. Elements in the
same vertical line have atomic
weights which differ by 16.

John Newlands-1864
Just four years before Mendeleev announced
his periodic table, Newlands noticed that there
were similarities between elements with
atomic weights that differed by seven. He
called this The Law of Octaves, drawing a
comparison with the octaves of music. The
noble gases (Helium, Neon, Argon etc.) were not
discovered until much later, which explains why
there was a periodicity of 7 and not 8 in
Newlands table. Newlands did not leave any
gaps for undiscovered elements in his table, and
sometimes had to cram two elements into one
box in order to keep the pattern. Because of
this, the Chemical Society refused to publish his
paper, with one Professor Foster saying he might
have equally well listed the elements
alphabetically.

Julius Lothar Meyer -1868
His first table contained just 28 elements, organized by
their valency (how many other atoms they can combine
with). These elements were almost entirely main group
elements, but in 1868 he incorporated the transition
metals in a much more developed table. This 1868 table
listed the elements in order of atomic weight, with
elements with the same valency arranged in vertical lines,
strikingly similar to Mendeleev’s table. Unfortunately for
Meyer, his work wasn’t published until 1870, a year after
Mendeleev’s periodic table had been published. Even
after 1870, Meyer and Mendeleev were still unaware of
each other’s work, although Meyer later admitted that
Mendeleev had published his version first.
Meyer did contribute to the development of the periodic
table in another way though. He was the first person to
recognise the periodic trends in the properties of
elements, and the graph shows the pattern he saw in the
atomic volume of an element plotted against its atomic
weight.

Dmitri Mendeleev- 1869
◦ Organized elements
by increasing
atomic mass.
◦ Elements with
similar properties
were grouped
together.
◦ There were some
discrepancies.

Dmitri Mendeleev (1869, Russian)
◦Predicted properties of undiscovered
elements.

Henry Moseley-1913
It wasn’t until 1913, six years after Mendeleev’s death
that the final piece of the puzzle fell into place. The
periodic table was arranged by atomic mass, and this
nearly always gives the same order as the atomic number.
However, there were some exceptions (like iodine and
tellurium, see above), which didn’t work. Mendeleev had
seen that they needed to be swapped around, but it was
Moseley that finally determined why.
He fired the newly-developed X-ray gun at samples of
the elements, and measured the wavelength of X-rays
given. He used this to calculate the frequency and found
that when the square root of this frequency was plotted
against atomic number, the graph showed a perfect
straight line. He’d found a way to actually measure atomic
number. When the First World War broke out, Moseley
turned down a position as a professor at Oxford and
became an officer in the Royal Engineers. He was killed
by a sniper in Turkey in August 15, and many people think
that Britain lost a future Nobel prize winner.
Organized elements by increasing atomic number.
Resolved discrepancies in Mendeleev’s arrangement.

1. How will you compare their ideas in the
arrangement of element in the periodic
table?
2. Who among them have common
insights about the existence of elements in
the periodic table?
 3. Among the contributions of the
scientists, which one do you think is more
acceptable nowadays?
QUESTIONS:

What are the importance of the
periodic table of elements?
ELLABORATE

ELLABORATE
There were several attempts even in the
early times to classify elements in a systematic
and logical arrangement that led to the
development of periodic table. Notable of the
early groupings are Lavoisier’s classification,
Dobereiner’s triad, Newland’s law of Octaves,
de Chancourtois’telluric helix, Meyer’s atomic
volume curve, Moseley’s work on atomic
number and Mendeleev’s periodic table.

EVALUATION
1. Among the scientists who were responsible for
the
Development of the periodic table are as follows:
I. Dmitri Mendeleev, II. Johann Dobereiner and
III. John Newlands. Arrange their names in order
of the history of the development of
the periodic table.
a. I , II, III c. III, I, II
b. II, III, I d. III, II, I

2. Who was the scientist who arranged the
elements into triads?
a. John Dalton
b. Johann Wolfgang Dobereneir
c. Dmitri Inovich Mendeleev
d. John Alexander Newlands

3. Who was the scientist who arranged the
elements in horizontal rows according to
increasing atomic masses with similar
properties?
a. John Dalton
b. Johann Wolfgang Dobereneir
c. Dmitri Inovich Mendeleev
d. John Alexander Newlands

4. The following are among the
early scientists who attempted to
classify elements in a logical
arrangement except _________.
a. Lavoisier
b. Newland
c. Bohr
d. Meyer

5. Which statement is TRUE about
Mendeleev’s contribution?
a. It is the major basis of the present day
periodic table.
b. He created Law of Octaves.
c. His contribution is the atomic volume curve.
d. He made major classifications of elements
excluding metalloids.

ASSIGNMENT:
Review for the upcoming
PERIODICAL TEST.

CO1g8.ppt

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