Electron Bonding and Structure

?

Shells and Orbitals

Shells and Orbitals

An orbital is the reigion around the nucleus that holds electrons with opposite spins.

  • Electrongs have fixed energies - they move in shells.
  • Each shell is given a principle quantum number.
  • The further away the shell is from the nucleus, the higher its energy level and the larger the principle quantum number.
  • Each shell is divided into sub-shells - S, P, D or F.
  • S - 1 orbital, max of 2 electrons.
  • P - 3 orbitals, max of 6 electrons.
  • D - 5 orbitals, max of 10 electrons.
  • F - 7 orbitals, max of 14 electrons.
1 of 8

Electronic Configuration

Electronic Configuration

The number of electrons an atom/ion has and how they are arranged.

This can be shown through...

1) Energy level diagrams

2) Sub-shell notation

1S 2S 2P 3S 3P 4S 4P 4D 4F

  • Rules
    • Electrons are adde one at a time.
    • The lowest energy level is filled first.
    • Each orbital is filled singularly before pairing.
    • An orbital holds up to two electrons maximum and each have opposite spins.
2 of 8

Shapes of Molecules (i)

2 electrons on central atom

  • 2 b.p - Linear 180°

3 electrons on central atom

  • 3 b.p - Trigonal Planar 180°
  • 2 b.p + 1 l.p - Distorted trigonal planar. 117.5° 

4 electrons on central atom

  • 4 b.p - Tetrahedral 109.5°
  • 3 b.p + 1 l.p - Pyramidal 107°
  • 2 b.p + 2 l.p - Non-linear 104.5°
3 of 8

Shapes of Molecules (ii)

5 electrons on central atom

  • 5 b.p - Trigonal Bipyramidal 90° + 120°
  • 4 b.p + 1 l.p - Distorted Trigonal Bipyramidal 87.5° + 117.5°

6 electrons on central atom

  • 6 b.p - Octahedral 90°
  • 5 b.p + 1 l.p - Distorted Octahedral 87.5°
  • 4 b.p + 2 l.p - Square Planar 90°
4 of 8

Intermolecular Forces

1) Induced Diplole-Dipole (van der waals)

Caused by the temporary movement of electrons - foundb between all atoms and molecules.

  • At any moment, electrons are more likely to be on one side than the other - this dipole can induce another temporary dipole in the opposite direction on a neighbouring atom. 
  • Larger molecule = more electrons, large dipole, therefore high m.p and b.p.

2) Permenant Dipole-Dipole 

Slightly negative and slightly positive atoms cause weak electrostatic forces of attraction between molecules - found in polar molecules.

3) Hydrogen Bonding

Can only happen when hydrogen is covalently bonded to a lone pair on oxygen, fluorine or nitrogen.

  • H has a high electron density, O, F and N are very electronegative so bond is polarised.
    • High b.p and m.p, ice is less dense.
5 of 8

Intramolecular forces - Ionic Bonding

1) Ionic Bonding

Electrostatic forces of attration between two oppositely charged ions.

  • Draw dot and cross diagrams to show this,

Giant Ionic Lattice

Each ion is surrounded by oppositely charged ions.

  • High m.p and b.p - strong electrostatic forces of attraction, more energy needed to overcome them.
  • Conducts electicity when molten - when molten, ions are free to move so can conduct the charge.
  • Soluble in polar solvents - attracted to oppositely charged ions, pulls ions away from the lattice and dissolves.
6 of 8

Intramolecular forces - Metallic Bonding

Metallic Bonding

Attraction of positive ions and delocalised electrons.

  • High m.p and b.p - attraction between ion and electron is strong.
  • Electrical conductivity - delocalised electrons can move freely both when solid and molten.
  • Malleability and ductility - can be drawn into wires, hammered into thin sheets and atoms can slide over each other.
  • Alloys - in order to modifty metal properties.
7 of 8

Intramolecular forces - Covalent Bonding and Dativ

Covalent Bonding

Formed by a shared pair of electrons.

  • Dot and cross diagrams.

Dative/ Co-ordinate Bonding

Both electrons come from one atom only.

  • Dot and cross diagrams (with arrows).
8 of 8

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Bonding & shapes resources »