Download Henry Moseley, the Atomic Number, and Synthesis

Henry Moseley, the Atomic Number, and
Synthesis of Elements
by Mc Roedel Asiri on June 14, 2017
lesson duration of 5 minutes
under Physical Science
generated on June 14, 2017 at 07:54 pm
Tags: Physical Science
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Generated: Jun 15,2017 03:54 AM
Henry Moseley, the Atomic Number, and Synthesis of Elements
( 2 hours and 5 mins
)
Written By: Mc Roedel Asiri on January 13, 2017
Subjects: Physical Science
Tags: Physical Science
Resources
ADDITIONAL RESOURCES:
Giunta, C. (2010). Atoms are Divisible: The Pieces Have Pieces. In C. Giunta (Ed.), Atoms in Chemistry: From Dalton's
Predecessors to Complex Atoms and Beyond (pp. 65-81), ACS Symposium Series 1044. American Chemical Society:
Washington, DC.
Bohr atomic model. (2015). In Encyclopædia Britannica Online. Retrieved October 27, 2015 from
http://www.britannica.com/science/Bohratomic-model
Chadwick discovers the neutron. (1998). Retrieved October 27, 2015 from
http://www.pbs.org/wgbh/aso/databank/entries/dp32n...
Chronology of Discoveries in Atomic Structure. (n.d.) Retrieved October 27, 2015 from
http://www.chemteam.info/AtomicStructure/HistAtomi...
Henry Moseley. (2014, December 29). Retrieved October 27, 2015 from http://www.famousscientists.org/henrymoseley/
Rutherford atomic model. (2015). In Encyclopædia Britannica Online. Retrieved October 27, 2015 from
http://www.britannica.com/science/ Rutherford-atomic-model
Thomson atomic model. (2015). In Encyclopædia Britannica Online. Retrieved October 27, 2015 from
http://www.britannica.com/science/ Thomson-atomic-model
Making new elements. (2013). Retrieved May 20, 2016 from http://www.popsci.com/science/article/2013-04/maki...
Gopalan, R. (1999). Elements of nuclear chemistry. New Delhi: Vikas Publishing House PVT LTD.
Discovery of the new chemical elements with numbers 113, 115, 117 and 118. (2016). Retrieved May 20, 2016 from
http://www.jinr.ru/posts/ discovery- of-the-new-chemical-elements-with-numbers-113-115-117-and-118-2/
(1) Coyne, Glynis L. (2012). Lead to Gold, Sorcery to Science: Alchemy and the Foundations of Modern Chemistry.
University of North Carolina PIT Journal, 4. Retrieved October 10, 2015 from http://pitjournal.unc.edu/article/lead-goldsorcery-sciencealchemy-and-foundations-modern-chemistry;
(2) see additional resources at the end of the lesson
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Content Standard
The learners demonstrate an understanding of :
1. How the concept of the atom evolved from Ancient Greek to the present
2. How the concept of the element evolved from Ancient Greek to the present.
Performance Standard
The learners can make a creative representation of the historical development of the atom or the chemical element in
a timeline.
Learning Competencies
Write the nuclear reactions involved in the synthesis of new elements
Explain how the concept of atomic number led to the synthesis of new elements in the laboratory
Cite the contributions of J.J. Thomson, Ernest Rutherford, Henry Moseley, and Niels Bohr to the understanding of the
structure of the atom
Overview of the objectives and key names or terms 10 mins
Overview of the objectives and key names or terms
1. Introduce the following learning objectives using any of the suggested protocols (Verbatim, Own Words, Readaloud)
a. I can point out the main ideas in the discovery of the structure of the atom and its subatomic particles
b. I can cite the contribution of John Dalton toward the understanding of the concept of the chemical elements.
c. I can explain how Dalton’s theory contributed to the discovery of other elements
2. Introduce the list of some important terms and names that learners will encounter:
a. Robert Boyle f. Chemical Atomic Theory
b. corpuscle g. 3 Fundamental Laws
c. Antoine Lavoisier h. Joseph Gay-Lussac
d. chemical element i. Amedeo Avogadro
e. John Dalton j. Dmitri Mendeleev
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Making Your Own Periodic Table; review about Dmitr 10 mins
Making Your Own Periodic Table
Make your own periodic table using the hypothetical elements that are given in the clues. Explain the word/s that will
be formed if you arrange the symbols of the elements correctly.
a) P and Pr both have one electron each. Pr has a bigger atomic size.
b) Od, Ri, and E are in the same series as P, C, and I. In terms of atomic size, P is the biggest while C is the smallest.
E is a metal while I is a non-metal. Od is smaller than Ri in atomic size.
c) O has a bigger atomic size than E in the same group. Y is also a bigger atom than C in the same group. R is more
nonmetallic than Pe but more metallic than Ti.
REVIEW (10 MINS)
4. Recall and expound on how Dmitri Mendeleev created a classification of elements based on their atomic weight. He
found that organizing the elements at the time by their calculated weight demonstrated a periodic pattern of both
physical and chemical properties, such as luster, physical state, reactivity to water, and others.
Henry Moseley and the atomic number; synthesis of
50 mins
Introduce Henry Moseley who was a researcher at Rutherford’s laboratory. In 1913 Moseley used Rutherford’s work
to advance the understanding of the elements and solve the problem with Mendeleev’s periodic table.
Explain that organizing the elements by their weight did not always give a periodic alignment of their chemical
properties. Moseley noticed that shooting electrons at elements caused them to release x-rays at unique frequencies.
He also noticed that the frequency increased by a certain amount when the “positive charge” of the chosen element
was higher. By arranging the elements according to the square root of the frequency they emitted, he was able to draw
out an arrangement of elements that more correctly predicted periodic trends.
Mention the experimental evidence he gave to an existing hypothesis: that the elements’ atomic number, or place in
the periodic table, was uniquely tied to their “positive charge”, or the number of protons they had. This discovery
allowed for a better arrangement of the periodic table, and predicted elements that were not yet discovered. His
method of identifying elements by shooting electrons and looking at x-rays became a very useful tool in characterizing
elements, and is now called x-ray spectroscopy.
Synthesis of Elements The invention of the device called cyclotron paved the way for transmuting one element into
another artificially. The high-energy particles that are produced from the cyclotron upon hitting heavy target nuclei
produce heavier nuclei.
The bombarding of Mo with deuteron formed technicium which is the first artificially made element. Its name is derived
from the Greek word technetos which means artificial.
The Transuranic Elements
Transuranic elements are synthetic elements with atomic numbers higher than that of Uranium (Z = 92).
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Neptunium (Z = 93) – synthesized by E.M. MacMillan in 1940
Plutonium (Z = 94)
The Superheavy Elements
Superheavy elements are elements with atomic numbers beyond 103. These are produced by bombarding heavy
nuclear targets with accelerated heavy projectiles.
Bohrium (Z = 107) – projectile used was Cr
Practice 40 mins
Write the nuclear reactions involved in the synthesis of each of the following new elements.
a) Curium (Z = 96) was formed by reacting Pu – 239 with alpha particles 42He. It has a half-life of 162 days.
b) Mendelevium (Z = 101) was formed by reacting En – 253 with alpha particles.
c) Meitnerium (Z = 109) was formed by cold fusion which involves the combination of Bi and Fe nuclides at ordinary
temperature.
Enrichment 5 mins
Read the following related texts.
a) Making New Elements http://www.popsci.com/science/article/2013-04/maki... Retrieved: May 20, 2016
b) Discovery of the new chemical elements with numbers 113, 115, 117 and 118 http://www.jinr.ru/ posts/discovery- ofthe-new-chemical-elements-with-numbers-113-115-117-and-118-2/ Retrieved: May 20, 2016
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Short Essay, Multiple Choice 10 mins
A. Short Essay (maximum of 3 sentences)
1) Dmitri Mendeleev is often regarded as the Father of the Periodic Table. Would you say that Henry Moseley
deserves the recognition more than him?
2) Explain why the atomic number is called the “fingerprint” of elements.
3) How would you relate alchemy to synthesis of new elements?
B. Choose the letter of the correct answer, and then write the nuclear reaction. Identify the element.
An isotope of element 102, with a mass number of 253 was produced by bombarding 24096Cm with a projectile, which
was absorbed by the target nucleus. This projectile should be ___
a) 52He b) 136C c) 126C d) 168O
Download Teaching Guide Book 0 mins
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