the periodic table

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the periodic table
2011-11-04 13:52:48

chapter 4
Show Answers:

  1. define element
    substance that cannot be split up into simpler substances by chemical means
  2. what did davy discover?
    sodium, potassium, calcium, barium, strontium, magnesium
  3. what is dobereiner associated with?
  4. define triad
    group of three elements with similiar chemical properties in which the atomic weight of the middle element is approx. equal to the average of the other two
  5. what is newlands associated with?
  6. define octaves
    groups of elements arranged in order of increasing atomic weight, in which the first and the eight element of each group have similair chemical properities
  7. what is mendeleev's periodic law?
    when elements are arranged in order of increasing atomic weight (ram), the properties of the elements vary periodically
  8. how was mendeleev different to newlands?
    • >he left gaps to make the elements fit into the proper column
    • >in a few cases he had to reverse the order of elements in order to make them fall into groups of elements with similiar properties
  9. define atomic number
    number of protons in the nucleus of that atom
  10. how ia the modern periodic table arranged?
    in order of increasing atomic number
  11. differences between modern periodic table and mendeleevs
    • >modern.. increasing atomic number
    • mend... increasing atomic weight (ram)
    • >more elements in modern
    • >no gaps in modern
    • >modern.. transition elements listed in seperate block
  12. define mass number
    sum of the number of protons and neutrons in the nucleus of an atom of that element
  13. who built the mass spectrometer
    francis william aston
  14. define isotopes
    atoms of the same element with the same number of protons but different number of neutrons in the nucleus