Physical Science Lesson Packet - Capitol University

**CAPITOL UNIVERSITY**  Cagayan de Oro City SENIOR HIGH SCHOOL **LESSON PACKET** SUBJECT: **PHYSICAL SCIENCE** ESSENTIAL TOPICS: **Origin and Formation of the Elements** **TOPIC 1:** The Origin of the Light Elements **TOPIC 2:** The Origin of the Heavy Elements **TOPIC 3...

**CAPITOL UNIVERSITY**  Cagayan de Oro City SENIOR HIGH SCHOOL **LESSON PACKET** SUBJECT: **PHYSICAL SCIENCE** ESSENTIAL TOPICS: **Origin and Formation of the Elements** **TOPIC 1:** The Origin of the Light Elements **TOPIC 2:** The Origin of the Heavy Elements **TOPIC 3**: Understanding the Life Span of Stars **LESSON CODE: L1W1** LEARNING OBJECTIVES: \- explain and give evidence for the formation of light elements in the big bang theory; - describe and give evidence for the formation of heavier elements during star formationandevolution;and \- write the nuclear fusion reactions in stars, which led to the formation of new elements **Key UNDERSTANDING** The big bang model provides an explanation for the formation of light elements, which later evolvedintoheavier elements through stellar evolution. **DISCUSSION** While looking at the night sky, one might wonder what the purpose of stars is. Do theyjust provideillumination or just beautify the nighttime sky? Stars may appear small to an observer on Earth, but theyhavea significant purpose for life on the planet. Their biggest role involves the formation of elements, andthereforethe origin of all matter. How the universe and everything in it came about were initially explained through speculations andmyths.The scientists, later on, approached these topics by proposing a model for which a sphere of inconceivableproperties burst in a \"big bang\", scattering its contents outward the vast space. This massive, primordialexplosion is believed to be the origin of matter as we knew it. **THE ORIGIN OF THE LIGHT ELEMENTS** The emergence of the universe brought about the formation of elements, and consequentlyof matter.One of the most popular attempts to describe the early universe is the big bang theory. It was first proposed,though not named, by Belgian astrophysicist and priest Abbe Georges Edouard Lemaitre (1894-1966). Thebigbang theory postulates that the universe emerged from a state of enormous density and energy. Thename"big bang" was coined by British astronomer Fred Hoyle in 1949. The big bang theory was madeinresponseto Einstein's work. **Three key observational pieces of evidence support the big bang model:** a\. Hubble or cosmic expansion, b\. Cosmic microwave background (CMB) c\. Primordial or big bang nucleosynthesis (BBN). Hubble and his assistant, Milton Humason, formulated Hubble\'s law, which proved that theuniversewas expanding, thereby suggesting that it was once compact. Hubble\'s law (also known as Hubbleexpansion),which states that other galaxies are moving away relative to the Milky Wat at a rate proportional todistance,was the first observational evidence of Lemaitre\'s big bang model. In the 1940s, theoretical physicist and cosmologist George Gamow, together with Robert HermanandRalph Alpher, predicted that if the early stage of the universe was hot and dense, then anafterglowofradiation must have filled up the universe because of the cooling process. This afterglowis detectedtodayascosmic background radiation, also known as the cosmic microwave background (CMB).  The \"light elements\" include hydrogen (H) and its isotope deuterium, helium-3, helium-4, andlithium-7.At approximately 10 kelvin and within the first second after the big bang, protons (nuclei of hydrogen),elections, and neutrons formed and moved with too much energy. As the universe expanded, thetemperaturedecreased, forming a stabilized number of protons and neutrons, with protons outnumberingtheneutronsin7:1 ratio. After about a minute, the temperature further decreased just enough for protons andneutronstocollide and stick together to form the nuclei of deuterium. Occasional collisions of these nuclei ledtotheformation of helium nuclei; and rarely, lithium nuclei. As the temperature continued to fall rapidly, andwithahigher number of protons in the early universe, hydrogen became the most abundant (about 75percent),while helium constituted 25 percent. There were also traces of lithium nuclei. **THE DISCOVERY OF COSMIC MICROWAVE BACKGROUND (CMB)** When the universe was young, photons were linked to matter because of the dense andhot conditions.Three hundred thousand years later, the temperature declined to less than 3000 Kelvin. This resultedintheformation of atomic hydrogen and the release of photons. Around 1940, George Gamow, together withhiscolleagues, hypothesized that the cooling process after the big bang generated electromagnetic (EM)wavesthat fill the universe. Radio astronomers, Penzias and Wilson, who were evaluating the performance of thenewradiotelescope to be used in trans-Atlantic telephone communications, detected a small, unexplainedsignal. Atthesame time, astrophysicists Robert Dicke, Jim Peebles, and David Wilkinson fromPrinceton Universityweresetting up their experiment to search for the background radiation, and they, too, found a small, unexplainedsignal whatever the direction the radio telescope was pointed. It was only in 1964 that they becameawarethat the noise in their telescope was in fact cosmic microwave background (CMB) radiation that waspostulatedby the big bang model. The two groups decided to publish their joint results. The Princeton group soon completedtheirmeasurements, verifying the work of Penzias and Wilson. In 1978, Penzias and Wilson receivedtheNobel Prizein Physics for their discovery of CMB.  **THE ORIGIN OF THE HEAVY ELEMENTS** **Which elements emerged from stellar nucleosynthesis?** Hydrogen atoms first produced in the big bang would need additional protons and neutronstobecomehelium or lithium. In a nucleus, protons and neutrons are held together by a strong force, whichovercomesand opposes the repulsion between protons. Protons can also be combined with neutrons toformheaviernuclei in a process called nuclear fusion. The atoms formed in the big bang merged into large clouds of gas. These clouds begantocontractunder their own gravity, leading to star formation. Consequently, the heavier elements formedinsidestarsandscattered in space because of instabilities and explosions. New elements came into being duringandaftertheexplosions. Nucleosynthesis in stars is called stellar nucleosynthesis, which is responsible for theformationofheavy elements. The two key processes of stellar nucleosynthesis are nuclear fusion and neutroncapture,bothof which will be discussed in the later parts of this chapter Nuclei of different elements from boron to iron formed from nuclear fusion. Nuclei heavier thanironemerged from neutron capture in conjunction with beta decay. Nuclear fusion and neutroncapturerequireenergy. Respectively. To fully recognize the processes that form heavy elements, one must understand the lifespanof stars.**UNDERSTANDING THE LIFE SPAN OF STARS** In nuclear reactions, atoms collide with one another, a process that alters their atomic structuresandreleases an enormous quantity of energy. This mechanism explains why bright light emanates fromstarsandwhy they have extremely high temperatures. In essence, stars are fueled or powered by nuclearfusionreactions at their cores, processes that mostly involve the conversion of hydrogen to helium. Stellar nucleosynthesis depends on the mass of the star. Stars may be classified accordingtomassassmall, medium-sized, or massive. Small stars can merely transform hydrogen into helium. Stars, suchasthesun, are medium-sized whose hydrogen atoms are eventually depleted; their heliumatoms arefurtherconverted into carbon and oxygen. Stars whose mass is five times greater than that of the sunareconsideredmassive stars. Medium-sized and massive stars convert helium into carbon and oxygen once their hydrogenatomsrunout/ however, massive stars undergo further nuclear reactions. Oxygen and carbon fuse to formneon(Ne),sodium (Na), magnesium (Mg), silicon (Si), and sulfur (S). these elements are transformed mostlyint0calcium(Ca), iron (Fe), nickel (Ni), chromium (Cr), copper (Cu), and others. As they age, huge stars withdepletedcores and exhausted fuel supplies undergo supernova. Supernova is the explosion of a star, resultinginanextreme brightness and release of an exceedingly high amount of energy. This results in theformationofother elements heavier than iron. These elements are then ejected space, finally forming thebasisforthematter. **END** Reference: SCIENCE in Today's world for SHS Physical Science by Sibs Publishing House.