Formation of Elements in the Universe PDF

Formation of Elements in the Universe Learning Competencies: give evidence for and explain the formation of the light elements in the big bang theory; give evidence for and describe the formation of heavier elements during star formation and evolution; and write the nuclear fusion re...

Formation of Elements in the Universe Learning Competencies: give evidence for and explain the formation of the light elements in the big bang theory; give evidence for and describe the formation of heavier elements during star formation and evolution; and write the nuclear fusion reactions that take place in stars, which lead to the formation of new elements. Learning Objectives: explain the formation of light elements in the early universe through big bang nucleosynthesis; describe the formation of heavier elements during the formation and evolution of stars; and appreciate the importance of the discovery of atomic number which led to the synthesis of new elements. How do you think the universe was formed? BIG BANG THEORY Scientists believe that the formation of the universe began through the explosion of a single primordial atom which happened 13 billion years ago. It became a theory that also explains the continuous expansion of the universe. BIG BANG THEORY Contains a lot of particles inside, very hot, dense ball expansion continued, but much more slowly BIG BANG THEORY Due to the expansion of space and the universe, the temperature cooled and electrostatic forces took hold. This forces bind the protons and neutrons together to form light elements, Hydrogen & Helium, in the process called Big Bang Nucleosynthesis. Other elements such as Lithium and Beryllium were also formed during this process. Atoms and Elements What is the difference between atoms and elements? Atom Basic unit of matter. Everything is made from atoms. Element A pure substance that is made up of only one kind of atom and can be identified by its atomic number and chemical symbol.  Components of an Atom What makes up an atom? The ATOM At the center of all atoms is the Nucleus. The nucleus contains protons and neutrons. Protons (+): positively charged atomic particles Electrons (-): negatively charged atomic particles Neutrons: Uncharged (neutral) atomic particles Always remember! The ATOM The number of protons is the same with the number of electrons. The number of neutrons depends. In the example, 4 protons 4 electrons 5 neutrons What is this element called?  The ATOM This element is called Atomic number (protons & electrons) Mass number/ Atomic mass (protons + neutrons) Protons = 4 4+5 = 9 = Mass number/ Atomic mass Neutrons = 5  The ATOM NOTATION: Mass number/ Atomic mass (protons + neutrons) 9 Atomic number 4 (protons & electrons) Protons = 4 4+5 = 9 = Mass number/ Atomic mass Neutrons = 5 16 8 16 8 The Origin of Elements Big Bang/Primordial Nucleosynthesis - the origin of light elements Elements formed: Hydrogen, Helium, Lithium, and Beryllium Stellar Nucleosynthesis - the origin of heavy elements Elements formed: Carbon, Oxygen, Neon, Silicon, Magnesium, Iron, etc.  Origin of Light Elements Nucleosynthesis - is the process that creates a new atomic nucleus from proton and neutrons (nucleons). Big Bang/Primordial Nucleosynthesis - is the process of producing light elements shortly after the big bang.  Nuclear Fusion - is the process by which two or more atomic nuclei of light elements join together or “fuse” to form a single heavier nucleus. - Through this process, the light elements Hydrogen (H), Helium (He), and small amounts of Lithium (Li) and Beryllium (Be) were formed.  Nuclear Fusion The Isotopes produced during the Big Bang Nucleosynthesis were: H-1, H-2, H-3, H-4, and H-7. Isotopes are atoms that have the same atomic number as the original element but with different atomic mass or mass number. WHAT IS A STAR? A star is a ball of gas strongly held together by its own gravitational force. The sun, is the closest star to the Earth and is formed 4.5 billion years ago. A star’s life starts as clouds of gas and dust. Gravity pulls these clouds together. Various nuclear fusion reactions take place and drive the formation and development of stars. Stars with different masses grow and evolve throughout the different stages of their lives. HOW ARE STARS FORMED? The space is made up of large amounts of gas and dust called interstellar medium. Stars are formed from the accumulation (or accretion) of these clouds of gas and dust, referred to us molecular clouds. Gravity pulls these clouds of gas and dust together causing it to collapse. As it collapse, it become denser and this paved way to the formation of stars. The dense clouds of gas and dust are known as nebula –the birthplace of stars. STAGES IN THE FORMATION OF STARS How Do Stars Form? STAGES IN THE FORMATION OF STARS How Do Stars Form? PROTOSTAR Star formation theory states that stars are formed when a dense Nebula region of molecular cloud collapses. During this process, fragments of clouds contract and form a stellar core known as protostar. Protostar  Origin of Heavy Elements The density inside a star is great enough to sustain nuclear fusion for extended periods required to synthesize heavy elements. Stellar Nucleosynthesis - the formation of heavy elements by fusion of lighter nuclei in the interior of stars. Evolution of Stars  What are the elements that are formed in the Different Stages of a Star’s Life Cycle? Stage: Main Sequence star Nuclear fusion of hydrogen occurs in the core that convert hydrogen into helium. Four hydrogen atoms combined to form helium atom and a high energy gamma rays. Element formed: Helium (He)  What are the elements that are formed in the Different Stages of a Star’s Life Cycle? Stage: Red giant star Several nuclear reactions occur in this stage, including alpha particles and fusion of 3 alpha particles (Helium-4 atoms). Helium is converted to Carbon in the core, while hydrogen is converted to Helium in the shell surrounding the core. Element formed: Carbon (C)  What are the elements that are formed in the Different Stages of a Star’s Life Cycle? Stage: Supergiant star Carbon fusion occurs in this stage. The star undergoes a series of reactions as more alpha particles are fused to form heavier elements all the way to Iron in the core and in the shells around the core. The element Oxygen is formed from Carbon fusion; Neon from Oxygen fusion; Magnesium from Neon fusion; Silicon from Magnesium fusion until Iron is formed. Elements formed: Oxygen (O), Neon (Ne), Magnesium (Mg), Silicon (Si), Sulfur (S), Argon (Ar), Calcium (Ca), Titanium (Ti), Chromium (Cr), Iron (Fe)  What are the elements that are formed in the Different Stages of a Star’s Life Cycle? Stage: Supernova In this stage, the core is unable to further generate energy to resist gravity due to the formation of heavier elements. The gravity squeezes the core until the star explodes and releases high amount of energy into space enough to form elements heavier than Iron such as Thorium and Uranium, except Transuranium elements. Elements formed: Elements with atomic mass/weight heavier than Iron (Fe), except Transuranium elements. PIECES OF EVIDENCE The discovery of interstellar dusts and gasses which justifies the stages of stellar formation which are happening across the universe. Infrared radiation being emitted in the process of stellar formation serves as a strong indication that stellar nucleosynthesis is concurrent with stellar formation and evolution.