Elements

• Big Bang nucleosynthesis formed the light elements (H, He, and Li)
• Stellar formation and evolution formed the elements heavier than Be to Fe
• Stellar explosion, or supernova, formed the elements heavier than Fe
• The formation of different elements involved many nuclear reactions, including fusion, fission, and radioactive decay
• Proof of the formation of elements includes the amounts of H and He present in the universe today
• Singularity is a point in space and/or a moment in time where the universe was infinitely hot and dense
• Inflation is a theory of exponential expansion of space in the early universe, lasting from 10^-36 seconds
• Nucleosynthesis refers to the creation of new atomic nuclei from pre-existing nucleons, primarily protons and neutrons
• Recombination is the epoch at which charged electrons and protons first became bound to form electrically neutral hydrogen atoms
• Annihilation is a reaction in which a particle and its antiparticle collide and disappear, releasing energy
• Redshift is the displacement of spectral lines toward longer wavelengths in radiation from distant galaxies and celestial objects
• Cosmic microwave background is electromagnetic radiation left over from an early stage of the universe in Big Bang cosmology
• Atoms are the smallest unit of matter that have all the properties of an element, composed of protons, neutrons, and electrons
• The atomic number indicates the number of protons in an atom, which is equal to the number of electrons in a neutral atom
• The atomic mass is equal to the sum of the number of protons and neutrons
• Isotopes refer to atoms with the same atomic number but different atomic masses
• Ions, which are positively or negatively charged particles, have the same number of protons but a different number of electrons
• The origin of all naturally occurring elements falls into two phases:
• Big Bang or Primordial Nucleosynthesis: origin of the "light" elements
• Stellar Nucleosynthesis: origin and production of the "heavy" elements
• Nucleosynthesis is the process that creates new atomic nucleus from preexisting nucleons (protons and neutrons)
• Primordial or Big Bang Nucleosynthesis refers to the process of producing the "light elements" shortly after the Big Bang
• Through Nuclear Fusion, the light elements - Hydrogen (H), Helium (He), and small amounts of lithium (Li) and beryllium (Be) were formed
• Isotopes produced during the Big Bang Nucleosynthesis were H-1, H-2, H-3, H-4, and Li-7
• Heavy elements were formed billions of years after the formation of stars
• Stars are hot and dense enough to burn hydrogen-1 (1H) to helium-4 (4He)
• Formation of heavy elements by fusion of lighter nuclei in the interior of stars is called "stellar nucleosynthesis"
• There are many nuclear synthetic pathways or nuclear fusions to produce heavy elements:
• Carbon-Nitrogen-oxygen cycle
• Triple alpha process
• Proton-proton fusion
• Elements heavier than iron cannot be formed through fusion and are formed in a supernova, a massive explosion of a star
• In a supernova, heavy elements are created by neutron capture reaction, where more neutrons are added to existing nuclei instead of fusion of light nuclei
• Elements higher than iron require a tremendous amount of energy to be formed and were produced from a neutron capture reaction in a supernova
• There are 3 reactions that led to the formation of the elements: nucleosynthesis, fusion, and neutron capture reaction
• The reactions involved in the formation of elements are dependent on the atomic mass of the elements
• More energy and higher temperature are needed to form heavier elements
• Nucleosynthesis formed light elements, whereas fusion in stars formed elements with an atomic mass within the range of beryllium and iron
• Elements with an atomic mass higher than iron were produced from a neutron capture reaction in a supernova
•   Nuclear fusion- collide (+ and -)

  Nuclear Fission- repelling ( + and +, - and -