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9th Grade Chapter 5 Lesson 2

9th Grade Chapter 5 Lesson 2



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    9th Grade Chapter 5 Lesson 2 9th Grade Chapter 5 Lesson 2 Presentation Transcript

    • 9 th Grade Chapter 5 Lesson 2 Pgs. 120-131 For Student Use Only
    • Inside the Atom
      • Atoms are made up of small particles called sub-atomic particles
        • Subatomic Particles
          • Found in Nucleus:
            • Neutrons- carry no charge
            • Protons- carry a positive charge
          • Atomic Number= number of protons in an element
          • Isotope= atoms with different numbers of neutrons
    • Inside the Atom
      • Subatomic Particles:
        • Quarks- make up protons and neutrons
          • These were not known for a long time
          • There are 2 types of quarks:
            • Up quarks- has a 2/3 positive charge
            • Down quarks- has a 1/3 negative charge
            • It takes 3 quarks to make up a neutron or proton
    • Inside the Atom
      • There is another component of the atom
        • Electrons- negatively charges particles
          • Electrons do not seem to make up anything else
        • Electrons are arranged in an electron shell.
        • Energy levels divide the electron shells
    • Inside the Atom
      • Electron Shells
        • Electrons- energy levels hold more electrons and energy as they go farther away
        • When atoms have a charge:
          • Ions: an atom that lost or gained electrons
          • Anions: negative ions
          • Cations: positive ions
    • Inside the Atom
      • Atoms-
        • Neutrinos- little neutral one
          • No electric charge and little mass
      • Atomic Models:
        • Illustrate the internal structure of the atom
        • The atoms originally were drawn like hard spheres
    • Inside the Atom
      • Quantum Theory:
        • States that tiny particles such as electrons do not absorb or release energy in a smooth energy flow
        • Quantum: Energy is always absorbed or released in a discrete packet called a quantum
        • Electrons change shells or orbits as they gain or lose electrons.
    • Inside the Atom
      • Bohr Model:
        • Most famous model of an atom
      • Wave-Mechanical Model:
        • Electrons have the same structure of both waves and particles
      • Heisenberg Uncertainty Principle:
        • Explains where a certain electron will be at a certain place
    • Inside the Atom
      • Electron Cloud Model (aka- quantum mechanical model)-
        • Electrons do not have particular orbits, they are in a regions called orbitals
      • Atomic Measurement
        • Mass of Atom- this is the amount of “stuff” in an atom
        • Mass Number- number of protons and neutrons in an atom’s nucleus.
    • Inside the Atom
      • Mass Number Notes:
        • Always whole numbers
        • Represent whole particles
        • More mass= higher mass number
        • Creates Isotopes- isotopes have same number of protons, but different number of neutrons and leads to different mass numbers
    • Inside the Atom
      • Average Mass Number-
        • The isotopes (that exist naturally) are averaged together and relative to the percentage found in nature
        • It measures Atomic Mass Unit.
          • AMU= 1/12 the mass of a carbon-12 atom
    • Inside the Atom
      • Atomic Mass:
        • The average of all the isotopes of an element
        • This is what chemists use when they say atomic mass
        • This is also called the mass number
    • Inside the Atom
      • Nuclear Decay:
        • Isotopes of certain atoms give off radiation
        • Most atoms nuclei are stable, BUT some are not, the unstable atoms give off radiation
        • Unstable= an atom that is capable of changing into another atom
        • This unstable substance is called radioactive!
    • Inside the Atom
      • Decay Rate:
        • Half-life= the rate at which an atom breaks down
        • There are 2 main types of Radioactive Decay + Gamma:
          • Alpha Decay- made up of 2 neutrons and 2 protons that are released from the center of the atom
          • Beta Decay- when a neutron changes into a proton and an electron is ejected from the atom
          • Gamma Radiation- not part of radioactive decay- usually occurs after alpha or beta radiation
    • Inside the Atom
      • Radiation:
        • All types of radiation can affect human beings (in large amounts)
          • Alpha Particles:
            • Less dangerous- not as much energy
          • Beta particles:
            • More energy, more dangerous
          • Gamma Radiation:
            • Most powerful, most dangerous
    • Inside the Atom
      • Radiation:
        • We are constantly opposed to radiation that occurs naturally
        • Our bodies naturally fix themselves
        • Above a certain amount of radiation cancer and other health problems may occur,
        • Below a certain level of radiation there is no harm done
    • Inside the Atom
      • Radiation can be useful
        • How is radiation useful?
      • Nuclear Radiation:
        • Nuclear Fission:
          • In 1930’s discovered that by bombarding nucleus with neutrons they can split the nucleus
    • Inside the Atom
      • Nuclear Fission:
        • The splitting of an nucleus releases large amounts of energy
          • Scientists discovered that by bombarding a nucleus with neutrons it will divide
        • Nuclear Fission- when a nucleus splits
        • Chain Reaction- The nucleus splits and the neutrons hit other nucleuses and causes them to split
    • Inside the Atom
      • Nuclear Fission:
        • Critical Mass- there must be a certain amount of fissionable material to create a chain reaction
          • Uncontrolled Fission- in an atomic bomb
          • Controlled Fission- in a nuclear reactor it creates useful energy
          • Breeder Reactors- produce more nuclear fuel than they use
    • Inside the Atom
      • Nuclear Fission:
        • Chernobyl- a site if a big accident caused by a series of mistakes
      • Nuclear Fusion:
        • The joining of nucleuses releases large amounts of energy
        • Sun is powered by fusion
        • Fusion is harder to produce than fission
        • Hydrogen Bomb is nuclear fusion