Physical Science lesson module for secondary

Physical science

1. Physical Science Quarter 1 – Module 1: Formation of Heavy Elements

2. What I Need to Know This module will walk you through the beginning of everything. It focuses on how some elements known today were formed same as when stars were born right after the universe existed. You will be provided with activities such as filling out graphic organizer, reading story board and illustrations which make you remember the lesson.

3. • Lesson 1 – Stellar Nucleosynthesis: Rise of the Stars! After going through this lesson, you are expected to: 1. explain stellar nucleosynthesis; 2. describe the different stages of life cycle of stars; 3. cite the different heavy elements formed in each stages of star cycle; 4. describe how heavier elements formed during stellar nucleosynthesis and evolution.

4. Have you also wondered what stars are made of? What keeps them shining so bright? Are there also stars that do not spark? You might also be asking the same questions ever since you were little that until now you still seek answers for. Well, this lesson will help you understand some of the important concepts about stars. Are you ready? Let’s go!

5. What I Know Choose the letter of the best answer in each item and write it on a sheet of paper. 1. Which of the following is the most accepted theory about the formation of the universe that explains why it continues to expand? a. big bang theory c. steady state theory b. divine creation theory d. oscillating theory 2. Which of the following is not considered as light elements? a. helium c. lithium b. hydrogen d. iron 3. Which of the following is TRUE about nucleosynthesis? a. It is the division of atomic particle b. The combination of elements to form compound c. It is the creation of everything including all matter in universe d. It is the process of creating new atomic nuclei from pre-existing nuclei 4. Which process is responsible for the formation of light elements such as Hydrogen and Helium? a. big bang nucleosynthesis c. supernova nucleosynthesis. b. stellar nucleosynthesis d. terrestrial nucleosynthesis

6. 5. Which element is the lightest and at the same time the most abundant in outer space? a. hydrogen c. lithium b. helium d. iron 6. How do heavier elements formed? a. Though combustion c. Through nuclear fusion b. Through nuclear fission d. Through nuclear synthesis 7. Which element can be formed when three atoms of helium are fused? a. carbon c. oxygen b. hydrogen d. silicon 8. Which of the following elements DOES NOT belong to the group? a. beryllium c. iron b. silicon d. oxygen 9. Which process is responsible for the formation of elements at the center of star? a. big bang nucleosynthesis c. stellar nucleosynthesis b. nuclear fusion d. supernova nucleosynthesis 10. How Elements heavier than iron are formed? a. big bang nucleosynthesis c. stellar nucleosynthesis b. solar nucleosynthesis d. supernova nucleosynthesis

7. 11. Which element will be formed when Carbon atom is combined with Helium atom? a. magnesium c. oxygen b. neon d. silicon 12. Why do average stars have longer life span than massive star? a. They have less fuel to burn c. They burn their fuel at faster rate b. They have more fuel to burn d. They burn their fuel at slower rate 13. Which phase of star life cycle is our sun? a. main sequence star c. red giant b. planetary nebula d. white dwarf 14. Which of the following contains only heavy elements? a. carbon, lithium, neon b. carbon, silicon, magnesium c. carbon, beryllium, helium d. helium, carbon, hydrogen 15. In which stage do massive stars explode and release large amount of energy? a. main sequence c. super nova b. protostar d. white dwarf

8. answers A D C A A C A A C D C B A B C

9. Stellar Nucleosynthesis: Rise of the Stars! The world where we live today is just a small part of our universe. In your previous years, you have learned about the different theories of the origin of the universe that eventually led to the formation of galaxies, solar system and other heavenly bodies. This lesson will focus on one of those wonderful things present in outer space, the stars. Although stars are millions of light years away from us, we can still see them twinkling in the night sky. Let’s find out how they emit light and what keeps them shining for a long time.

10. Stellar Nucleosynthesis The word “stellar” means star and the formation of elements in the center of the star is called stellar nucleosynthesis. All stars form in nebulae, which are huge clouds of gas and dust. Though they shine for many thousands, and even millions of years, stars do not last for ever. The changes that occur in a star over time and the final stage of its life depend on a star's size.

11. Nuclear reactions at the center (or core) of a star provides energy which makes it shine brightly. This stage is called the 'main sequence '. The exact lifetime of a star depends very much on its size. Very massive stars use up their fuel quickly. This means they may only last a few hundred thousand years. Smaller stars use up fuel more slowly so will shine for several billion years. Eventually, the hydrogen which powers the nuclear reactions inside a star begins to run out. The star then enters the final phases of its lifetime. All stars will expand, cool and change color to become a red giant. What happens next depends on how massive the star is. A smaller star, like the Sun, will gradually cool down and stop glowing. During these changes it will go through the planetary nebula phase, and white dwarf phase. After many thousands of millions of years it will stop glowing and become a black dwarf. A massive star experiences a much more energetic and violent end. It explodes as a supernova. This scatters materials from inside the star across space. This material can collect in nebulae and form the next generation of stars. After the dust clears, a very dense neutron star is left behind. These spin rapidly and can give off streams of radiation, known as pulsars. If the star is especially massive, when it explodes it forms a black hole.

12. Average Star 1. The star is unable to generate heat when it runs out of hydrogen in its core leading to its contraction and expansion. It cools down and glows red. The Helium fused into Carbon. The star is now RED GIANT 2. Red giant star becomes exhausted of nuclear fuel, the outer material is blown off into space leaving the inert Carbon. The remnant is known as WHITE DWARF . 3. Giant cloud of gas and dust known as NEBULA. 4. It is formed from nebula due to the gravity that pulled Hydrogen gas together until it spins faster and faster and becomes ignited. A PROTOSTAR rises. 5. MAIN SEQUENCE STAR starts to form when nuclear fusion occurs at the core of the star, it begins to contract, glow and become stable. Hydrogen is converted into Helium. 6. This is said to be the remain of the white dwarf that cooled down and no longer emits light and heat. The hypothetical BLACK DWARF .

13. Massive star 1. It is believed that a NEUTRON STAR is formed from supernova explosion. This is also the smallest star 2. Explosion of star or SUPERNOVA releases large amount of energy. Because of that, elements are dispersed into the space. 3. BLACK HOLE is a region in space where gravity is too strong that no matter can escape from it. 4. A more massive main sequence star evolves, cools and expands faster than low mass star and will turn into RED SUPER GIANT star, the largest known star. Carbon fusion still occurs and Oxygen formed.

14. MODULE 2

15. https://www.youtube.com/watch?v=HdPzOWlLrbE

16. Big Bang Theory Summary Early in the Big Bang, it was a tiny elementary particle. As the Universe expanded and cooled, there was a period of proton-proton chain reaction wherein protons were fuse into Helium. The Universe ran into a problem. Red giant cores get past this via the Triple-Alpha process, but the Universe expands right through this possibility and the density/temperature are quickly too low to synthesis any additional elements.

17. Concept of Atomic Number that Led to the Synthesis of New Elements in the Laboratory

18. All matter in the universe is made from tiny building blocks called atoms.

19. Do you have any idea how the different elements on the periodic table were formed, known and identified?

20. ELEMENTS Elements are made up of tiny particles, the neutron , proton and electron . Hydrogen and Helium are the elements that exist in the early beginning.

21. Key stages of Big Bang Theory Singularity A point of infinite density and gravity, and that before this event, space and time did not exist. Nucleosynthesis It was the nuclear fusion and the formation of new nuclei a ctions in the early stages of development of the universe . Recombination A period of time during which charged electrons and protons first became bound to form electrically neutral hydrogen atoms. It is the formation of the capture of free electrons by the cations in a plasma.

22. KEY POINTS The atomic number is the number of protons (positively charged particles) in an atom. Henry Gwyn-Jeffreys Moseley was an English physicist who demonstrated that the atomic number, the number of protons in an atom, determines most of the properties of an element. In 1919, Ernest Rutherford successfully carried out a nuclear transmutation reaction a process of transforming one element or isotope into another element. In 1925, there were four vacancies in the periodic table corresponding to the atomic numbers 43, 61, 85, and 87 . Elements with atomic numbers 43 and 85 were synthesized using particle accelerators.

23. A particle accelerator is a device that is used to speed up the protons to overcome the repulsion between the protons and the target atomic nuclei by using magnetic and electrical fields. It is used to synthesize new elements. Elements with atomic numbers greater than 92 (atomic number of uranium) are called trans-uranium elements They were discovered in the laboratory using nuclear reactors or particle accelerators. 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.

24. Hydrogen, H , was named by Laviosier and is the most abundant element on the periodic table. H has an atomic mass of 1.00794 amu (atomic mass unit), which makes hydrogen the lightest element on the periodic table. H is followed by He(Helium), Li(Lithium), Be( Berilium ) and so on and so fort because atomic weight is used to arrange elements from lightest to heaviest.

25. HOW ELEMENTS FORM WITH THE ATOMIC CONCEPT He is Henry Moseley Why?

26. He was an English physicist whose experiment demonstrated that the major properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus.

27. Henry Moseley 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. 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.

28. 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.

29. He used X-ray spectroscopy to determine the atomic number of an element. He bombarded a beam of electrons to different elements and measured their X-ray spectral lines. His results clearly showed that frequency of the X-rays given off by an element was mathematically related to the position of that element in the Periodic table. The frequency is proportional to the charge of the nucleus, or the atomic number.

30. When the elements were arranged according to their atomic numbers, there were four gaps in the table. These gaps corresponded to the atomic numbers 43, 61, 85, and 87. These elements were later synthesized in the laboratory through nuclear transmutations.

31. Discovery of Nuclear Transmutation

32. In 1919, Ernest Rutherford successfully carried out a nuclear transmutation reaction — a reaction involving the transformation of one element or isotope into another element. The first nuclide to be prepared by artificial means was an isotope of oxygen, 17O. It was made by Ernest Rutherford in 1919 by bombarding nitrogen atoms with α particles: 147 N + 4 2 α → 17 8 O + 1 1 H However, both alpha particles and atomic nuclei are positively charged, so they tend to repel each other. Therefore, instead of using fast-moving alpha particles in synthesizing new elements, atomic nuclei are often bombarded with neutrons (neutral particles) in particle accelerators.

33. James Chadwick discovered the neutron in 1932, as a previously unknown neutral particle produced along with 12C by the nuclear reaction between 9Be and 4He: 49 𝐵𝑒 + 42 𝐻𝑒 → 126 𝐶 + 10 𝑛

34. The first element to be prepared that does not occur naturally on the earth, technetium, was created by bombardment of molybdenum by deuterons (heavy hydrogen, H12), by Emilio Segre and Carlo Perrier in 1937: 12 𝐻 + 4297 𝑀𝑜 → 2 01 𝑛 + 4397 𝑇𝑐

35. The first controlled nuclear chain reaction was carried out in a reactor at the University of Chicago in 1942. One of the many reactions involved was: 23592 𝑈 + 10 𝑛 → 8735 𝐵𝑟 + 14657 𝐿𝑎 + 3 10 𝑛

36. The Discovery of the Missing Elements

37. Recall that in 1925, there were four vacancies in the periodic table corresponding to the atomic numbers 43, 61, 85, and 87 . Two of these elements were synthesized in the laboratory using particle accelerators. A particle accelerator is a device that is used to speed up the protons to overcome the repulsion between the protons and the target atomic nuclei by using magnetic and electrical fields. It is used to synthesize new elements. In 1937, American physicist Ernest Lawrence synthesized element with atomic number 43 using a linear particle accelerator. He bombarded molybdenum (Z=42) with fast-moving neutrons. The newly synthesized element was named Technetium (Tc) after the Greek word " technêtos " meaning “ artificial .” Technetium was the first man-made element.

38. The bombarding of Mo(molybdenum) with deuteron formed TECHNETIUM which is the first artificially made element. 4297𝑀𝑜 +21𝐻→ 4397𝑇𝑐 + 10𝑛 In 1940, Dale Corson, K. Mackenzie , and Emilio Segre discovered element with atomic number 85. They bombarded atoms of bismuth (Z=83) with fastmoving alpha particles in a cyclotron. A cyclotron is a particle accelerator that uses alternating electric field to accelerate particles that move in a spiral path in the presence of a magnetic field. Element-85 was named ASTATINE from the Greek word “ astatos ” meaning unstable.

39. The two other elements with atomic numbers 61 and 87 were discovered through studies in radioactivity. Element-61 (Promethium) was discovered as a decay product of the fission of uranium while element-87 (Francium) was discovered as a breakdown product of uranium.

40. The Synthesis of the Elements

41. 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 Universe ran into the Be problem. Red giant cores get past this via the Triple-Alpha process, but the Universe expands right through this possibility and the density/temperature are quickly too low to synthesis any additional elements.

42. Chemical Evolution of the Universe

43. Chemical Evolution Not quite down to Big Bang abundances, but we are getting pretty close and still looking. Low-mass stars synthesize `new’ He, C, O during the main sequence, RGB, HB and AGB phases. These freshly minted elements are brought to the surface via convection and redistributed via stellar winds and planetary nebulae into the interstellar medium to be incorporated into later generations of stars.

44. Chemical Evolution II For more massive stars, `equilibrium’ fusion reactions produce elements all the way up to Fe. Freshly made elements are delivered via stellar winds or, sometimes more spectacularly via supernova explosions

45. Chemical Evolution III What about the trans-Fe elements? Equilibrium fusion reactions of light elements don’t proceed past Fe because of Fe’s location at the peak of the curve of binding energy. However, in certain circumstances, supernovae for example, nonequilibrium reactions can build elements beyond Fe in the Periodic Table. Many of these are radioactive, but some are stable.

46. Neutron Capture Elements There are two principle paths to building the elements heavier than Fe. Both use the addition of neutrons to existing `seed’ nuclei (neutrons have no charge so are much easier to add to positivelycharged nuclei). S-process (slow addition of neutrons) R-process (rapid addition of neutrons )

47. The S-process can produce elements up to #83 - Bismuth. There are peaks in the Solar System abundance of heavy elements at 38Sr, 56Ba and 82Pb. These are easily understood in the context of the S-process and `magic’ numbers of neutrons. The site of the S-process is AGB start during and between shell flashes. The no source is a by-product of C 13 +He 4 -> O 16 43Tc is an s-process nucleus and proof that it is in operation in AGB stars.

48. The R-process The R-process is the Rapid addition of neutrons to existing nuclei. Rapid here means that many neutrons are added before a betadecay occurs. First build up a VERY heavy isotope, then, as beta-decays occur, you march up in atomic number and produce the REALLY HEAVY STUFF. For this to happen, a big burst of neutrons is needed. The most promising place with the right conditions is in a SNII explosion right above the collapsed core.

49. At the end of 1940, element-94 was synthesized by Seaborg, McMillan, Kennedy, and Wahl. They bombarded uranium with deuterons (particles composed of a proton and a neutron) in a cyclotron. Element-94 was named plutonium. Elements with atomic numbers greater than 92 (atomic number of uranium) are called trans-uranium elements. Hence, neptunium and plutonium are both trans- uranium elements. They are unstable and decay radioactively into other elements. All these elements were discovered in the laboratory as artificially generated synthetic elements. They are prepared using nuclear reactors or particle accelerators. In the next lesson, you will learn the nuclear reactions involved in the synthesis of these trans-uranium elements.

50. Stellar nucleosynthesis This is the process by which elements are created within stars by combining the protons and neutrons together from the nuclei of lighter elements. Fusion inside stars transforms hydrogen into helium, heat, and radiation. Heavier elements are created in different types of stars as they die or explode.