Heavier elements

2. • is a broad term encompassing the various branches of natural
science that study non-living systems.
• It comprises four general areas:
• Physics, Astronomy, Chemistry, and the Earth sciences.

7. WEEK 1

8. FORMATION AND
SYNTHESIS OF HEAVIER
ELEMENTS

9. Pretest:

10. OBJECTIVES:
• give evidence for and describe the formation of heavier elements
during star formation and evolution
• demonstrate understanding of how the concept of atomic number led
to the synthesis of new elements in the laboratory

11. What are elements?

14. Have you ever wonder where does elements
came?
• To understand this better lets understand first the beginning of the
universe.

15. THE BEGINNING OF THE UNIVERSE

16. Stages of development of the universe
• Singularity
• Big bang
• Radiation era
• Matter era

22. • At the very beginning of everything, there was nothing but an
intensely hot and infinitely dense point, a few millimeters wide.
• The matter that makes up everything that we see and know today
was packed into this point.
• It has been described as being similar to a supercharged black
hole.

25. • Approximately 13.7 billion years ago, the tiny point that is
the singularity violently exploded.
• It is this explosion that we typically call the big bang.
• This explosion is the source of all matter, energy, space
and time.
• EXPANSION NOT explosion

29. The time after the big bang up to the present
moment and beyond can be broadly described
into two

30. Radiation era
This era is so named for the abundance of
radiation after the big bang and spanned only
the first tens of thousands of years since the
explosion abundance of radiation after the big
bang and spanned only the first tens of
thousands of years since the explosion

31. The era can be said to comprise of smaller epoch stages, most of
which lasted less than even a second.
❖ Planck Epoch: During this time, there was Planck Epoch: During this time, there was no matter, only a
superforce that would later become the major forces we see today. At the end of the Planck epoch,
gravity was formed. The epoch is so named because it took place in the smallest measurable unit of
time, Planck time.
❖ Grand Unification Epoch: 10-43 seconds after the big bang, strong nuclear force separated from the
superforce.
❖ Inflationary Epoch: 10-36 seconds after the big bang, during the inflationary epoch, a rapid expansion
took place in the universe. The universe was still intensely hot and had only particles like electrons and
quarks.
❖ Electroweak Epoch: In this epoch, 10-32 seconds after the big bang, electromagnetic force and weak
nuclear force broke off the superforce.
❖ Quark Epoch: 10-12 seconds after the big bang, the universe was filled with particles needed to form a
complex system, but the temperature and density were still too high to support it.

32. ❖ Hadron Epoch: At 10-16 seconds after the big bang, the temperature
lowered enough to 1010
K for the formation of protons and neutrons from
quarks.
❖ Lepton Epoch: At about one second after the big bang, the temperature
was at 1012
K.
❖ Nuclear Epoch: 100 seconds after the big bang, the temperature was at
109
K, and the conditions were sufficient for the formation of nuclei from
protons and neutrons. Helium atoms were thus created.

33. MATTER ERA
Once the universe was capable of and had sufficient
conditions to form elements, the matter era was
ushered in, where matter predominates the universe.
This era spans the millions of years after the
radiation era when the universe has grown and
changed and transformed into the form that we see
today.

34. ❖ Atomic Epoch: The atomic epoch was 50,000 years after the big bang. The universe
finally cooled down to 3,000 K, a temperature sufficient to support electrons and
nuclei combining to form atoms. The recombination process resulted in the creation
of Hydrogen atoms.
❖ Galactic Epoch: Fast forward to 200 million years after the big bang, atomic clusters
were formed, which would much later become galaxies.
❖ Stellar Epoch: 3 billion years after the big bang, stars began forming inside the
galaxies. The universe developed into the form that we see now in this epoch. All the
other elements were formed, then planets were formed, life took shape. This epoch is
also called the Stelliferous Era, and includes the present day, up and until a point in the
future when stars will cease being formed.

35. STAR CYCLE
❖ The life cycle of any star from birth to death, and all the stages in
between, will span millions or billions of years. This is why stars don’t
seem to change at all, because a human lifetime is a snippet of
fraction of a blink of an eye to these giants.
❖ The path to be followed by a particular star depends mainly on its
mass, or how much gas collected and collapsed to form a star,
because that material will serve as a star’s fuel.

36. The amount of matter
that forms the star
determines the
amount of fuel, and
through a variety of
other factors, the
lifetime and eventual
fate of the star.

37. As we may remember from physics and
chemistry, when nuclei collide with enough
energy to overcome the electromagnetic
repulsion between them, the stronger
nuclear force take place, and they fuse
small fraction of their mass converting into
a huge amount of pure energy, as dictated
by E equals mc squared.

38. Nuclear Fusion
reactions power the Sun and
other stars. In a fusion reaction,
two light nuclei merge to form
a single heavier nucleus. The
process releases energy
because the total mass of the
resulting single nucleus is less
than the mass of the two
original nuclei. The leftover
mass becomes energy
Therefore, only by colliding nuclei
together and fusing them in its
ultrahot core can a star release
enough outward energy to counter
the effects of gravity relentlessly
crushing inward.

39. LOW MASS OR AVERAGE STAR
Given that mass is the key factor
here, let’s start with a low mass
star. This would range from the
smallest that stars can be,
meaning the smallest amount of
material that can sufficiently
trigger nuclear fusion to qualify
as a star, which is about thirteen
Jupiter masses, to a star
somewhere in the ballpark of
our sun’s mass.

42. ❖ In the earliest era of star
formation, this material
was almost exclusively
hydrogen and helium, as
this was the remains
after the brief seventeen
minutes of
nucleosynthesis soon
after the Big Bang.
H
HE
❖ This matter collects due to
gravity, pushing increasingly
inward as it contracts, until things
get so hot over a few millions of
years. That nuclear fusion
eventually begins, establishing
equilibrium and generating a
yellow or red main sequence star
that glows with all energy
released from the collision
happening inside.

43. ❖ This fusion reaction begins with two
protons fusing, followed by subsequent
beta decay, to get proton and neutron,
and we call this deuteron, which is a
nucleus of heavy hydrogen
❖ Such a star will continue in this
manner for a billions of years,
slowly fusing all of the hydrogen in
its core into helium and
maintaining a relatively the same
size, temperature and luminosity as
it does so, until almost all the
hydrogen is gone. At this
point,things really begin to change.

44. ❖ The core of the star will shrink and get
hotter, which make the remaining hydrogen
burn even faster and all that extra energy
being generated will be radiated outward
and push the outer layer away from the
core.
❖ As the outer layers expand, they cool
and thus become more and more red,
and the star become of what we called
the red giant star. The star can
maintain this new status for a little
while longer around a billion years but
after almost all hydrogen is gone the
core even gets smaller and even
hotter.
RED GIANTS

45. ❖At this stage a phase called helium flash
things are so hot that the stars are able to
fuse this heavier helium nuclei into larger
nuclei like carbon and oxygen through
something called the triple alpha process and
this means that the star has whole new
source of fuel in all the helium it has been for
billions of years.
The stars begin pulsating as it runs
through its final energy reserve
entering what we call the horizontal
branch and in this time it becomes
smaller, hotter and bluer until at last
much of the helium has been fused
into larger nuclei.

46. ❖ Once the core is predominantly carbon and
oxygen with just a shell of helium around it
and a shell of hydrogen around that, the star
has very few materials left to burn, so the
core will collapse and the star enters the
asymptomatic giant branch.
❖ This means it will grow rapidly and become a
giant star again, until the last burst of energy
ejects to the outer layer pushing it away
from the core and back into interstellar
medium, leaving only a tiny very hot bare
core behind about the size of the Earth.
❖ This will gradually cool as it has no more fuel to burn
not being enough to fuse carbon or oxygen nuclei and
it will contract further until we are left with a white
dwarf star. The material in these white dwarf star will
then become available to join more gas particle to
form yet another star.
PLANETARY NEBULA
WHITE DWARF

47. Stars - High
Mass Stellar
Evolution
❖ Now for a high mass star, one that
is much more massive than our
sun, things are quite different.
❖ Their demise will not be so quiet.
Big star goes out with a bang!

48. ❖ Things start out normally with a gas cloud
collecting under the influence of gravity.
❖ Simply, it means that this cloud will be
much larger than those that form a low mass
stars, so it will contain much more mass.
❖ More mass means more gravity, which
means the force pushing inward is much
stronger and star gets much hotter.
❖ A hotter temperature means faster fusion
which generates greater outward pressure
to counteract the greater inward pull of
gravity.

49. ❖ This will result in a main sequence of star that is
hot, big, bright, and blue. This is where things start
to go differently from low mass stars.
❖ Low mass stars take billions of years to use up all
their fuel, high mass stars are much hotter and
burn their fuel much faster. That means they use
up all the hydrogen in their cores a hundred million
years only.
❖As the fuel starts running out, the core
contracts and heats up producing
more energy so the star well swell up
into a giant star just like we saw in a
low mass stars.

50. ❖ But while the core of a high mass star continues
to compress, it gets much hotter than the core of
a low mass star and it becomes able to fuse
helium nuclei to form carbon and then oxygen,
neon, silicon each heavier nucleus being
relegated to a smaller and smaller region of the
core that is hot enough to fuse it.
❖ All the way at the center sits the heaviest
element that can be fused within a star, iron.
Because a high mass star (> 4 Solar Masses)
has considerably more gravity than low mass
stars, several shell burning stages can occur
(about 333,000 earth)

51. ❖ But there is a limit. Iron
cannot fuse, and when it
tries the end result is a
highly compacted core and
intense temperatures.
❖ The core density is 4 x
1017 kg/m3. This is very
degenerate and cannot be
compressed further.
❖ The intense heat generated
by this compression (core
bounce) blows the star
apart in a type II
supernova.

52. CRAB NEBULA
❖ The classic supernova remnant is the
Crab nebula.
❖ The end result of a supernova is three
fold:
❖ Heavy elements created in the
explosion
❖ Intense interstellar wind
❖ A neutron star (or black hole) stellar
remnant

53. Post activity:
Question:
If you are a star, what will be the path you
want to choose? A low mass star or a heavy
mass star? Why? Explain your answer in not
less than 5 sentences.

54. 1. Which of the following is a stellar core formed when
the fragments of a collapsed molecular cloud
contract?
A. protostar
B. supernova
C. red giant
D. main sequence star

55. 2. The formation of a star starts with the dense regions of
molecular clouds. What force pulls matter together to
form these regions?
A. magnetic force
B. nuclear force
C. electromagnetic force
D. gravitational force

56. 3. What happens when most of the hydrogen in the core
is fused into helium in the stellar core?
A. Hydrogen fusion stops, and the pressure in the core decreases.
B. Hydrogen fusion continues, and the pressure in the core
increases.
C. Gravity squeezes the star until helium and hydrogen burning
occur.
D. Nuclear energy increases until carbon and helium burning
occur.

57. 4. Arrange the following stages of stellar evolution of a
low-mass star.
A. Protostar> main sequence star> red giant> white dwarf
B.Protostar> main sequence star> white dwarf >red giant>
C. Main sequence star> red giant> white dwarf> protostar
D. Main sequence star> protostar> red giant> white dwarf

58. 5. Which of the following is the major factor predicting
the fate of a star?
A. strength of gravitational force
B. mass of the star
C. amount of iron produced
D. temperature of the star

59. 6-7. The two elements formed during the creation of a low
mass star.
8-10. Name at least 3 heavy elements that were formed
during the formation of the heavy mass star.
II. Identification.

60. PERFORMANCE TASK: The life of a star
❖ Since the topic is on Star Formation or
Nucleosynthesis you are tasked to make an artwork
on the Life of a Star. You can make a drawing,
painting, digital painting, clay model and etc.

61. Rubricks:
Creativity-25%
Work ethics-25%
Originality-25%
Presentation-25%
Total=100%

62. Assignment:
1.Explain Moseley’s X-ray Spectroscopy
2. What is nuclear Transmutation?

64. SYNTHESIS OF ELEMENTS

65. ❖ Remember that each element has a distinctive spectrum unlike any other element, you can identify the element
in a light source by analyzing the light through a spectroscope and looking for characteristic patterns.
❖ Thus, the atomic spectra can help us identify elements like fingerprints to identify people.
❖ The spectrum serves as a characteristic property (something like a fingerprint) for each element, which allows
scientists to identify the elements present in a sample.
Dmitri Ivanovich Mendeleev (often romanized as Mendeleyev or Mendeleef)
-was a Russian chemist and inventor. He is best remembered for formulating
the Periodic Law and creating a farsighted version of the periodic table of
elements. He used the Periodic Law not only to correct the then-accepted
properties of some known elements, such as the valence and atomic weight of
uranium, but also to predict the properties of eight elements that were yet to
be discovered.

68. He was an English physicist, whose contribution
to the science of physics was the justification
from physical laws of the previous empirical and
chemical concept of the atomic number. This
stemmed from his development of Moseley's law
in X-ray spectra.
Henry Gwyn Jeffreys Moseley
As he continued his study, he measured the x-ray spectral lines of an element as he
bombarded a beam of electrons to different elements to determine its atomic number. He
then believed that frequency of the X-rays given off by an element was mathematically
related to the position of that element in the Periodic table.

69. 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.
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.
Elements were then arranged
according to their atomic numbers but
there were four gaps in the table
(atomic numbers 43, 61, 85, and 87).
The four missing elements were later
created in the laboratory through
nuclear transmutations.

70. Moseley’s X-ray Spectroscopy

71. Discovery of Nuclear Transmutation
• In 1919, Ernest Rutherford carried out a reaction in
which one element was transformed into another
element. In the reaction, alpha particles were
bombarded from radium directed to the nitrogen nuclei.
He showed that the nitrogen nuclei reacted to the alpha
particles formed some oxygen nuclei. This reaction is
called nuclear transmutation.
7
14
𝑁 + 2
4
𝛿 → 8
17
𝑂 + 1
1
𝑃
13
27
𝐴𝑙 + 2
4
𝛿 → + 0
1
𝑛

73. • The nuclear transmutation was successfully done but both the
alpha particles and atomic nuclei are positively charged, so they
tend to repel each other. Because of this, atomic nuclei are often
bombarded with neutrons (neutral particles) in particle
accelerators in synthesizing new elements.
3
6
𝐿𝑖 + 0
1
𝑛 → 1
3
𝐻 +

74. The Discovery of the Missing Elements
In 1925, there were four gaps in the periodic table corresponding to
the atomic numbers 43, 61, 85, and 87. Using particle accelerators,
two of these elements were synthesized in the laboratory. Particle
accelerator is a device used to synthesize new elements using
magnetic and electrical fields. It speeds up the protons to overcome
the repulsion between the protons and the target atomic nuclei.

75. • Carlo Perrier and Emilio Segre synthesized the first artificially prepared element,
Technetium (Element 43), by bombardment of Molybdenum by deuterons in a particle
accelerator
42
97
𝑀𝑜 + 1
2
𝐻 → 43
97
𝑇𝑐 + 20
1
𝑛

76. • Astatine (element with atomic number 85) was first produced in 1940 by
Dale Corson, K. Mackenzie and Emilio Segre. It was synthesized by
bombarding bismuth with fast-moving alpha particles in a cyclotron. The
scientists found that the isotope they created was radioactive, so they
named the element using the Greek ‘astatos’ meaning unstable.
• Through studies in radioactivity, the two other elements with atomic
numbers 61 and 87 were discovered.
• Promethium (element 61) was recovered from the leftovers of uranium
fission while Francium (element 87) was discovered as a breakdown
product of uranium.

77. Transuranic Elements
• Transuranic elements are synthetic elements
with atomic numbers higher than that of
Uranium(Z = 92).
82
208
𝑃𝑏 + 26
58
𝐹𝑒 → 108
265
𝐻𝑠 + 0
1
𝑛
1. 92
238
𝑈 + 0
1
𝑛 → 93
239
𝑁𝑝 + −1
0
β-Neptunium
2. 92
238
𝑈 + 1
2
𝐻 → 93
239
𝑁𝑝 + 20
1
𝑛
93
239
𝑁𝑝 → 94
238
𝑃𝑢 + −1
0
β- Plutonium

78. 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
83
209
𝐵𝑖 + 24
54
𝐶𝑟 → 107
261
𝐵ℎ + 20
1
𝑛

79. Alchemy
• Alchemy is the very old study and philosophy of how to change
basic substances (such as metals) into other substances.
• It also studied how substances (and how they are changed into
other substances) were related to magic and astrology.
• People who studied alchemy were called alchemists.
• Basically, it is a form of chemistry and speculative philosophy
practiced in the Middle Ages and the Renaissance and concerned
principally with discovering methods for transmuting baser metals
into gold and with finding a universal solvent and an elixir of life.

81. Activity:
Direction: Fill up the missing in the
given equation
1. 96
242
𝐶𝑚 + → 98
245
𝐶𝑓 + 0
1
𝑛
2. 13
27
𝐴𝑙 + 2
4
𝛿 → + 0
1
𝑛
3. 3
6
𝐿𝑖 + 0
1
𝑛 → + 2
4
𝛿
4. 92
238
𝑈 + 2
4
𝛿 → + 0
1
𝑛
5. 2
4
𝛿 + → 5
10
𝐵 + 0
1
𝑛

83. Assignment:
Directions: Write a short essay (maximum of 5 sentences) for each
question. Do this in your notebook.
1. Explain why the atomic number is called the “fingerprint” of
elements.
2. How would you relate alchemy to synthesis of new elements?
3. How did the conceptof atomic number led to the synthesis of new
elements?
4. Can you create elements? Support your answer
5. What are the different types of chemical bonding? Explain each
Type