PHYSCI

• BIGBANG THEORY - universe started from a hot and dense single point called singularity
• BING BANG NUCLEOSYSNTHESIS - elements formed during Big bang
• Atom - composed of subatomic particles 


  proton - positive

  electron - negative

  neutron - neutral

  nucleus - neutrons & protons
• ISOTOPES - elements have diff numbers of neutrons but same number of protons
• STELLAR NUCLEOSYNTHESIS - elements formed through energy released by stars
• STELLAR NEBULA - birthplace of stars
• STELLAR NEBULA - a huge cloud of dust and particle
• Hydrogen gain enough energy to collide and combine to form Helium through NUCLEAR FUSION
• [DALTONS MODEL- THE BILLIARD BALL MODEL]

  1807, Dalton presented evidence that matter was discrete and must exist as particles
• [DALTONS MODEL- THE BILLIARD BALL MODEL]

  His Major Hypotheses

  1. Each element composed of atoms (small indivisible particles)

  • identical for each element but different from atoms of other element
• [DALTONS MODEL- THE BILLIARD BALL MODEL]

  His Major Hypotheses

  2. These particles are featureless spheres of uniform density

  • he pictured atom as tiny indivisible, uniformly dense, and solid sphere
• [THOMSON -PLUM PUDDING MODEL]

  1903, JJ Thomson discovered electrons
• [THOMSON - PLUM PUDDING MODEL]

  His experiments shows that electron has a mass of 9.11 x 10 ^-31 kg and a charge of 1.60 x 10^-19 C
• [THOMSON - PLUM PUDDING MODEL]

  • produced rays using several different has types in cathode ray tubes
  • concluded that these ray consists of electrons
• [THOMSON - PLUM PUDDING MODEL]

  • He concluded that all atoms contained electrons
  • Also concluded that electrons were stuck randomly in homogenous mass of positively charged "pudding"
• [THOMSON - PLUM PUDDING MODEL]

  • Since atom as a whole is neutral, some other parts must be positive
• [THOMSON - PLUM PUDDING MODEL]

  • His model of atom was a sphere of positive charged in which negatively charged electrons were embedded
• [ERNEST RUTHERFORD'S MODEL - NUCLEAR MODEL]

  1911, Rutherford discovered 99.97% of mass of atom was concentrated in a tiny core called nucleus
• [ERNEST RUTHERFORD'S MODEL - NUCLEAR MODEL]

  • Rutherford's model envisioned electrons circulating around a positively charged core
• [ERNEST RUTHERFORD'S MODEL - NUCLEAR MODEL]

  • His envisioned atom as a dense center of positive charge (nucleus) around which electron orbited
• [MICROWAVES]

  • EM radiation that have low frequencies
• [DISCOVERY OF MICROWAVES AS A COOKING TOOL]

  • 1946, Raytheon Corp. engineer, Percy Spencer put his chocolate bar close to microwave source
• [XRAYS]

  • Discovered by German physicist Wilhelm Roentgen in 1895
• [XRAYS]

  • discovered x rays by noticing a piece of fluorescent paper was glowing
• [XRAYS]

  • Roentgen deduced that some unknown radiation was the cause
  • called X-radiation
• [XRAYS]

  >>> EARLY USE OF XRAYS

  • far too aggressive, resulting to cancer
• [EARLY THOUGHT ABOUT ELEMENTS]

  • Greek philosophers were the first people to speculate about basic substances of matter
  • Aristotle said that matter consist of 4 elements air, fire, earth, and water (wrong)
• [SYMBOLS OF ELEMENTS]

  • Jons Jacob Berzelius (Swedish chemist) (early 1800s) used 1 or 2 letters of latin name to designate elements
• [THE ATOM]

  • all matter is composed of atoms
  • protons (+) electrons (-) neutrons (=)
  • Nucleus contain proton and electron
  • Electrons surround nucleus
  • electrons and protons have equal but opposite charges
• [THE ATOMIC NUCLEUS]

  • Protons and Electron have the same mass and 2000 times massive than electron
• [THE ATOMIC NUCLEUS]

  >>>> DISCOVERY

  1. Electron - JJ Thomson (1897)
  2. Proton - Ernest Rutherford (1918)
  3. Neutron - James Chadwick (1932)
• [ATOMIC DESIGNATIONS]


  1. Atomic Number (Z)

  • number of protons
  • always the same for given
  • designates the number of electrons
  • ION -- element gains/loses electrons
• [ATOMIC DESIGNATIONS]


  2. Mass Number (A)

  • protons + neutrons
  • total no. of neutrons
• [DETERMINING THE COMPOSITION OF AN ATOM]

  Mass Number (A) = Neutrons + Atomic Number (Z)
• [ATOMIC MASS]

  • weighted avg mass of atom
  • measured in unified atomic mass units (u)
  • the weight of proton or neutron
• [DISCOVERY OF ELEMENTS]

  • earliest civilizations isolated 12 elements: gold, silver, lead, copper, tin, iron, carbon, sulfur, antimony, arsenic, bismuth and mercury
• [DISCOVERY OF ELEMENTS]

  • Phosphorus was isolated (urine) in 1669
  • 1st element whose date of discovery is known
• [DISCOVERY OF ELEMENTS]

  • 1746, platinum, cobalt, zinc were discovered
• [DISCOVERY OF ELEMENTS]

  • 1808, Davy (English chemist) used electricity ti invent a battery to break down compounds, thereby isolating 6 addtl elements (Na, K, Mg, Ca, Ba, Sr)
• [DISCOVERY OF ELEMENTS]

  • 1895, 73 elements were known