physci

• The origin of all the naturally occurring elements fall into two phases: Big Bang or Primordial Nucleosynthesis and Stellar Nucleosynthesis.
• The origin of all the naturally occurring elements fall into two phases: Big Bang or Primordial Nucleosynthesis and Stellar Nucleosynthesis.
• The "light" elements, such as Hydrogen (H), Helium (He), and small amounts of lithium (Li) and beryllium (Be), were present during the initial formation of the universe.
• Nucleosynthesis is the process that creates new atomic nucleus from pre-existing nucleons, which is proton and neutrons.
• The formation of heavy elements by fusion of lighter nuclei in the interior of stars is known as stellar nucleosynthesis.
• The density inside a star is great enough to sustain fusion for extended time periods required to synthesize heavy elements.
• There are many nuclear synthetic pathways or nuclear fusions to produce heavy elements, including Proton-proton fusion, Carbon-Nitrogen-oxygen cycle, and Triple alpha process.
• Layers near core of stars have very high temperatures enough to nucleosynthesize heavy elements such as silicon and iron.
• Heavy elements cannot be formed through fusion as tremendous amounts of energy are needed for the reaction to occur.
• In a neutron capture reaction, heavy elements are created by addition of more neutrons to existing nuclei instead of fusion of light nuclei.
• Heavy elements are formed in a supernova, a massive explosion of a star.
• The concept of Atomic Number led to the synthesis of new elements in the laboratory.
• Alpha particles have atomic number of 2 and atomic mass of 4.
• Neutron has 0 atomic number and 1 atomic mass.
• Technetium is the first artificial element.
• Big Bang or Primordial Nucleosynthesis is the origin of light elements
• Stellar Nucleosynthesis is the origin of heavy elements
• Nuclear Fusion is caused by high energy and temperature of the universe
• Isotopes has the same atomic number but with different atomic mass
• Democritus is also known as the Laughing Philosopher
• Democritus introduced the idea of atom as the basic building blocks of all matter.
• Democritus' idea has been called the best guess in antiquity since it is correct in many ways yet based on pure speculation.
• Different elements differ in their numbers of protons and electrons, which gives different physical and chemical properties.
• 1. Sweet substances are made out of smooth atoms and Bitter substances are made of sharp atoms.
• 2. Atoms of liquid are slippery.
• 3. Atoms of solid stick together
• 4. Atoms of gas spread out
• Aristotle rejected Democritus' idea of the atom
• John Dalton revived the idea of an atom in 1800
• Greeks believe that the smallest unit that anything could be divided to was the element.
• Aristotle named 4 elements:

  • fire
  • air
  • water
  • earth
• Philosophers who argued on the 4 elements:

  Thales: Water

  Heraclitus: Fire

  Anaximenes: Air
• Empedocles proposed that everything was made up of a mixture of the 4 elements.
• Experiment of Empedocles was setting light to a stick
• Alchemy attempts to convert base metals into gold to find a universal elixir
• Elixir is a magical or medicinal potion
• Atom:

  • basic unit of elements
  • smallest unit of matter
  • building blocks of chemistry
  • 3 subatomic particles
• Charge: Particles will exert on other charged particles
• + and - attracts
• + and + or - and - will repel