End of Topic Test - AS Bonding + IMF's

Bonding + IMF's. Tell me if I've got anything wrong. :)

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  • Created by: sebsq
  • Created on: 17-11-11 19:45

Types of Bonding

  • Ionic bonding - Electrostatic attraction between oppositely charged ions in a lattice.
  • Covalent Bonding - The electrostatic attraction between a shared pair of electrons and the protons in the nucleii of the bonding atoms.
  • Metallic Bonding - The electrostatic attraction between +ve metal ions and a sea of delocalised electrons.
  • Simple molecular - IMF's forming bonds between molecules causing them to form a lattice.

ALSO - Dative covalency (lone pair of electrons  in a molecule forming bonds with other atoms/molecules) is known as co-ordinate bonding. e.g. NH4+ or NH3BF3

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Covalent bonds

Remember: Covalent bonds between different atoms will be polar to some extent causing non-symmetrical covalent bonds.

e.g. Cl-H where Cl is delta (slightly) -ve due to a higher electronegativity of the Cl causing it to attract electrons more than H which becomes delta +ve

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IMF's - Van der Waals Forces (IDIDS)

NB: These instantaneous dipole induced dipole interactions occur in ALL molecules.

There are temporary dipoles due to uneven electron distribution due to the constant movement of electrons, this induces a temporary dipole in a neighbouring molecule, producing a temporary induced dipole-dipole attraction.

The bigger the molecule, (i.e. the more electrons), the greater the IDIDS (and therefore higher mbpts).

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Ionic Crystals

  • High mbpts due to lots of strong ionic bonds need a lot of energy to break.
  • Conduct electricity when molten/solution as ions free to move/carry charge.
  • Brittle as if ions shift down, it springs apart due to repulsion of other ions.
  • Soluble in water as ions hydrate + form strong IMF's with water
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Simple Molecular Crystals

  • Low mbpts as weak IMF's between molecules require little energy to break.
  • No electrical conductivity as no mobile charge carriers (ions/ free electrons).
  • Weak strength due to weak IMF's.
  • Soluble in solvents with similar IMF's.
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Giant Covalent Crystals

V.V. High mbpts - Each atom bonded to many others (e.g. diamonds tetrahedron) + lots of strong covalent bonds.

No electrical conductivity as no free electrons/ mobile charge carriers.

V. strong strength as each atom bonded to many others (e.g. diamonds tetrahedron).


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V.V.High mbpts  - Due to lots of strong covalent bonds needing lots of energy to break.

Conducts electricity - Free (delocalised) electrons - mobile charge carriers.

Strong within layers, weak (soft) between layers - Due to lots of strong covalent bonds needing lots of energy to break but only idids between layers.

Insoluble due to strong covalent bonds.

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Medium mbpts - Electrons are mobile allowing conduction of heat through ions.

Electrical conductivity when solid/molten - sea of de-localised electrons in these states.

Medium strength - Mobile electrons allow ion layers to slide over each other.

Insoluble - Strong lattice don't form bonds with solvents.

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IMF's -

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Olly Nural

Thanks for this! Helped quite a bit, and is useful just to find a list of them in one place :P

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