Chemistry IB

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Anonymous
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180268
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Chemistry IB
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2012-10-28 14:07:05
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chemisrty IB chem
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  1. Delocalized electrons
    A delocalized electron is an electron in a atom, ion or molecule not associated with any single atom or a single covalent bond.

    Delocalized electrons contribute to the conductivity of the atom, ion or molecule. Materials with many delocalized electrons tend to be highly conductive
  2. malleable
    • can be bent & reshaped under pressure 
    • Impurities disturb the lattice reducing malleability, therefore alloys are harder than pure metals
  3. ductile 
    • can be drawn into a thin wire
    • sliding positive ions again
  4. Ions
    • non-neutral atoms
    • lose or gain an electron
  5. Ionic Compounds
    Do not form molecules but rather 3D crystal lattice structure
  6. Conalent Bonds
    • Electrons be shared rather than transferred
    • non-metal with non-metal normaly
  7. non-polar covalent bond
    no electronegativity difference between atoms
  8. polar covalent bond
    • small elctronegativity difference
    • unless over 1.8 difference
  9. prefixes to 10
    • 1: mono (but only used for the second element) 2: di 3: tri 4: tetra 5: penta 6: hexa 7:hepta 8: octa 9: nona 10: deca
    • only used for nonmetals with nonmetals
  10. allotropes of carbon
    • diamond
    • graphite
    • buckminsterfullerene
  11. diamond
    • giant covalent structure
    • single molecule is very large
    • very hard and very high melting point
  12. graphite
    • layers of hexagonal rings
    • electrons delocalized between layers
    • good conductor of electriscity 
  13. Buckminsterfullerene
    • consists of 60 carbons arranged in hexagons & pentagons
    • led to nanotechnology science
  14. single bond
    when each non-metal shares an eectron the result is a single bond
  15. multiple bonds
    • occurs when more then one electron each is shared 
    • double bond = 2 electrons each
    • triple bond = 3 electrons each
  16. what does VSEPR stand for 
    valence shell electron pair repulsion
  17. AB2
    • shape = linear
    • bond angle = 180°
  18. AB3
    • shape =trigonal planer 
    • angle = 120°
  19. AB4
    • Shape = tetrahedral
    • angle = 109.5°
  20. AB2E
    • Shape = Angular
    • angle = 120° > x > 109.5°
  21. AB2E2
    • shape = Angular
    • angle = 109.5 > x > 90°
  22. AB3E
    • shape = Pyramidal
    • angle = 109.5 > x > 90°
  23. dipole
    A pair of equal and oppositely charged or magnetized poles separated by a distance.
  24. criteria to be polar
    • 1) must contain polar bonds
    • 2)arrangement of the bonds must be asymmetric. central atom has either
    • a) lone pair of electrons and/or
    • b) different atoms bonded to it
  25. Intermolecular forces
    • force of attraction between moleculars, much weaker than forces within molecules
    • the stronger the IMF the more energy is needed to separatethe molecules
  26. dipole-dipole forces
    A weak intermolecular force of attraction between a partial positive (d+) charge on one particle and a partial negative (d+) charge on a second particle.
  27. order to consider for IMF strength
    • 1) Polarity of molecukes
    • more polar has higer IMF
    • if both non-polar use #2
    • 2)molar mass of molecules
    • larger mass has higher IMF, if both are equal mass use #3
    • 3) Length of carbon chain
    • larger chain has higher IMF, branches on chains reduce IMF
  28. hydrogen bonding requires?
    • 1)very polar covalent bond of hydrogen and another small more electronegative element (flourine, oxygen or nitrogen)
    • 2) attraction of above δ+ hyerdrogen with a non-bonded electron pair of a flourine, oxygen or nitrogen atom in a neighbouring molcule
  29. volatility
    covalent molecules tend to be more volatile than ionic or metallic substances
  30. melting and boiling points
    • covalent molecules tend to boil at lower temperatures than ionic or metallic substances
    • non-polar molecules break away easier because of weak intermolecular forces
  31. texture
    • ionic substances are hard and brittle
    • covalent solids tend to be soft and waxy
  32. solubility
    • polar covalent bonds dissolve in water because water is also polar
    • ionic substances dissolve in water through a process called hydraration
  33. conductivity
    • ionic solids do not conduct elctricity unless thet are dissolved in water or/ are molten
    • covalent molecules do not conduct electricity since they have no free ions ot electrons

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