Physical Science

• Big Bang Theory


  The currently accepted theory of the origin of the universe which proposes that everything started from a singularity which in time inflated - and continues to do so - until the world we know of today started existing approximately 14 billion years ago
• No explosion of shrapnel and fire and no mushroom cloud
• Singularity


  Miniscule dense collection of energy
• Big Bang Nucleosynthesis


  1. All hydrogen and most helium in the universe was produced during the big bang event, starting ~100 seconds after the explosion

  2. Small amount of lithium was also produced

  3. As the universe cools, protons and neutrons can fuse to form heavier atomic nuclei

  4. Ceased within a few minutes after the big bag because the universe had expanded and cooled sufficiently by then such that the temperatures and pressures were too low to support additional nuclear fusion reactions
• Evidence of Big Bang Model

  • Redshift
  • The Relative Abundance of Light Elements in the universe
  • Cosmic Microwave Background
• Redshift


  Suggests that other galaxies are moving farther away from ours, later determined that they are not moving away instead, space itself is expanding in all directions causing all the galaxies to be relatively farther apart, used to learn how fast the universe is expanding
• The Relative Abundance of Light Elements in the universe

  Through measurements, we find that around 24% of the universe's ordinary matter is currently comprised of helium, about 74% of hydrogen, and 2% of other elements, the figures would only make sense if nucleosynthesis in the big bang model actually occurred since no chemical process significantly changes these percentages
• Cosmic Microwave Background


  The energy (thermal radiation) that was left as a result of recombination, atoms became neutral due to the binding of nuclei and electrons, the remaining radiation then begin to scatter and is now seen by scientists as a faint microwave glow emitted by any object in space
• Star


  A very hot ball of gas (plasma), created elements by combining lighter nuclei into heavier nuclei via nuclear fusion reactions in their cores and releasing energy in the process, natural nuclear reactors, giant stars have an 'onion layer' structure as you proceed deeper into the star, temperatures and pressures increase, and heavier and heavier nuclei are fused together
• Stellar Nucleosynthesis


  This is the birth of elements through nuclear fusion that takes place within stars, Enormous temperatures (15,000,000 K), pressures, and densities of matter are needed to initiate the fusion (thermonuclear) reactions which squeeze nuclei together and release energy, The basic nuclear reaction in the Sun converts hydrogen to helium and releases energy in the form of electromagnetic radiation
• Sun


  Only large enough to fuse hydrogen into helium within its core, stars much larger than the sun can fuse heavier elements from lighter elements
• Iron


  The heaviest element that can be made in a star, elements heavier than iron have fusion reactions with temperature and pressure requirements greater than those that can occur within the core of against star
• Supernova


  This is the explosion in the event of a death star
• Supernova Nucleosynthesis


  Elements heavier than iron (Z=26) are made primarily when giant stars explode in supernovae, when a star runs out of nuclear fuel (lighter nuclei) and can no longer undergo fusion reactions, gravity causes the star to collapse and it triggers a phenomenally large explosion called supernova, explosion of the star momentarily generates high enough temperatures and pressures to cause nuclear fusion and reactions that can make elements with atomic numbers 27-92 (Cobalt to Uranium), only the largest stars can explode in supernovae elements, elements with atomic numbers 27-92 are rarer than elements with atomic number 1-26
• Neutron-Star Mergers


  This is when stars merge to form a more massive star, generating more energy than normal stars
• Types of Elements


  • Light Elements (Hydrogen to Iron)
  • Heavy Elements (Heavier than Iron)
• Types of Nucleosynthesis


  • Big Bang Nucleosynthesis
  • Stellar (Star) Nucleosynthesis
  • Supernova Nucleosynthesis (not currently occurring in our universe)
• Nuclear Fusion


  Fusion = come together, making a larger nucleus from two or more small nuclei, elements in our universe relies on nuclear fusion reactions, smaller nuclei collide together to make larger nuclei, and energy is released in the form of electromagnetic radiation, requires high temperature and pressure beyond those found within earth, temperatures and pressures are found inside stars and did occur during the initial formation of our universe (big bang event), involves only the nuclei of atoms, matter exists as plasma at temperatures at which fusion occur, releases a lot of energy per gram of material; much more energy than is released by burning a comparable amount of wood, coal, oil, or gasoline
• Plasma


  Super high energy, electrically charged gas
• E=mc2


  Einstein's famous equation that is used when some of the mass of the nuclei is converted to energy during nuclei fusion
• Nuclear Fission


  Fission = split, making two or more smaller nuclei from a larger nucleus, elements can be formed when a large, unstable nucleus breaks apart in an attempt to achieve a more stable lower energy state, the splitting of nucleus to form two or more smaller, more stable nuclei is called nuclear fission, fission may occur spontaneously (without energy being added) or i may be prompted by firing a nuclear bullet (like a proton or neutron), fission also releases energy stored in the nucleus of an atom but is does not release as much energy as fusion does, the energy released per gram of material by fission is considerably more than the energy released by burning a comparable amount of wood, oil, gasoline, etc., fission of uranium-235 atoms is used in nuclear power plants to produce energy, fission naturally occurs within the layer of the earth as radioactive elements in rocks spontaneously decay to more stable elements, creating a natural source of heat within the earth, Humans also contain a small proportion of radioactive isotopes within the body. These isotopes decay naturally and release radiation. Therefore, humans are slightly radioactive, Bananas are also slightly radioactive
• Nuclear Bullet


  A proton or a neutron that is fired at an unstable nucleus
• Isotopes


  One of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with different atomic masses and physical properties, every element has one or more isotope, atoms with different numbers of neutrons
• Radioactivity


  The release of energy, in the form of energetic particles and waves, from the nuclei of unstable (Radioactive) isotopes, Radioactive atoms undergo fission-type reactions in order to try to become more stable nuclei with lower energies
• Radioisotopes


  What radioactive atoms are called, The nuclei of unstable, radioactive isotopes have the wrong ratio of neutrons to protons (n/p), Generally, it's too high, When n/p of an isotope falls between 1 to 1.5, the nucleus is stable (within the "Band of Stability" on a n0 vs. p+ plot), Outside of that range, nuclei tend to be unstable and break apart over time
• Radioactive Decay


  This "breaking apart" of unstable nuclei over time and the accompanying release of nuclear particles and energy
• Transmutation


  The general term for the changing of a chemical element or isotope to another by changing the number of protons and/or neutrons, fusion and fission reactions both qualify as transmutations, the bombardment of a nucleus by a nuclear bullet in order to change it into another element also counts as transmutation
• Radiation


  Particles and energies released during the decay of elements
• Synthetic Elements


  Refers to the chemical process formed in the laboratory through certain, man-controlled processes, elements with atomic number Z ≥ 93 are synthetic (man-made), elements are all radioactive meaning they decay over time to more stable elements, releasing radiation from their nuclei, Some have very short half-lives and have only existed for fractions of a second, Some synthetic elements have uses for mankind, The heaviest synthetic element has an atomic number of 118, it has no uses at present
• Transuranium Elements


  These are elements heavier than Uranium
• Atomic Number


  Number of protons in an atom, pertaining to its identity
• Atomic Weight


  The number of protons and neutron together of an atom
• Periodic Trends


  The chemical properties exhibited by the elements, reflected in the periodic table through groups of families
• Henry Moseley


  A scientist who sought to fix Dmitri Mendeleev's arrangement of the periodic table of elements after a discovery was made that arranging the elements based on their weight did not reflect the elements chemical properties properly
• Henry Moseley's X-ray Spectroscopy Experiment


  Experimented by shooting electrons at varying elements and found that the elements released x-rays at a certain frequency that increases as the protons increases, opted to arrange the elements in the periodic table according to the square root of their unique frequency emission resulting in a more organized table which shows periodic trends more clearly, Moseley's x-ray spectroscopy is vital in the synthesis of the heaviest elements in the laboratory because it serves as a foundation of discovering that manipulating an element's number of protons can be done
• Cyclotron


  A type of particle accelerator, a device invented and used to form and accelerate protons to hit a target nuclei, causing an addition of a proton to the target element
• Polarity


  Refers to the overall charge of a molecule
• Molecule


  A group of elements bonded together
• Positive Charge


  Refers to an atom or a molecule with an excess proton
• Negative Charge


  Refers to an atom or a molecule with an excess, unpaired electron