Bonding

• Ionic Bonding


  A bond between metals and non-metals. The metal will donate electrons to the non-metal in order to achieve a full outer shell and achieving noble gas status. This allows the molecules to be ionised, forming attraction towards one another due to opposite charge attraction via electrostatic forces

  
• Ionic Lattice

  The structure of an ionic compound. This allows the compound to be brittle and non-conductive in a solid state

  
• Covalent Bonding


  A bond between non-metals. The non-metals will share an electron each to form a single bond (or 2 for double and 3 for triple bonds). This can be maintained due to electrostatic forces maintaining their electron clouds

  
• Co-ordinate Bonding

  A bond by which a lone pair of electrons shares its pair with an atom that is electron deficient. This is a type of covalent bond, also known as dative covalent bonding

  
• Metallic Bonding


  A bond between metals. Consists of positive nuclei dispersed in a sea of delocalised electrons. Allowing the metal to be conducting at a solid state. This sea also allows the metal to be malleable and ductile

  
• Electronegativity


  The power of an atom to attract its electron density towards itself in a covalent bond

  
• N, O, F


  The only elements that create hydrogen bonds due to their high electronegativity
• Factors Affecting Electronegativity


  Affected by;

  - shielding - more = less electronegativity-

  - the nuclear charge - more = more electronegativity-

  - atomic radius - smaller = more electronegativity--
• Trend in Electronegativity


  Increases across a period and increases up a group

  
• Intermolecular Forces


  van der Waals, dipole-dipole and hydrogen bonding
• van der Waals


  The mimicking of electron clouds due to the constant changing of electron clouds, forming an instantaneous dipole. This occurs between all molecules at all times

  
• Dipole-Dipole


  The rotation of molecules due to molecules with a constant biased electron cloud. This causes like partial charge repulsion and opposite partial charge attraction. This only occurs between molecules with permanent biased electron clouds
• Permanent Dipole


  Biased electron cloud, represented by a lower-case delta
• Hydrogen Bonding


  A highly electronegative element will be bonded to hydrogen. This induces a biased electron cloud, giving the hydrogen a partially positive charge. This hydrogen then has opposite charge attraction between its partial positive charge and lone pairs on other molecules. This only occurs if the hydrogen is bonded to N, O or F. Note: this is why oxygen has a high surface tension
• Advantages of Hydrogen Bonding

  Allows for an alpha helix to form when considering the secondary structure of a protein. It also maintains the structure of the double helix in our DNA
• Electron Pair Repulsion Theory

  Electrons repel one another due to their like charges. This means that when bonded to molecules will be as far away as possible to one another, allowing us to determine the shapes of molecules
• Linear


  A shape of a molecule:

  - 2 bonding pairs

  - Occupies 2D space

  
• 180


  The bonding angle of "Linear"
• Trigonal Planar


  A shape of a molecule:

  - 3 bonding pairs

  - Occupies 2D space

  
• 120


  The bonding angle of "Trigonal Planar"
• Bent (V-Shape) Planar


  A shape of a molecule:

  - 2 bonding pairs, 1 lone pairs

  - Occupies 2D space

  
• 104


  The bonding angle of "Bent (V-Shape) Planar"
• Tetrahedral


  A shape of a molecule:

  - 4 bonding pairs

  - Occupies 3D space

  
• 109.5


  The bonding angle of "Tetrahedral"
• Trigonal Pyramidal


  A shape of a molecule:

  - 3 bonding pairs, 1 lone pair

  - Occupies 3D space

  
• 107


  The bonding angle of "Trigonal Pyramidal"
• Bent (V-Shape)


  A shape of a molecule:

  - 2 bonding pairs, 2 lone pairs

  - Occupies 3D space

  
• 104.5


  The bonding angle of "Bent (V-Shape)"
• Trigonal Bipyramidal


  A shape of a molecule:

  - 5 bonding pairs

  - Occupies 3D space
• 120 and 90


  The bonding angles of "Trigonal Bipyramidal" with 5BP
• seesaw


  A shape of a molecule:

  - 4 bonding pairs, 1 lone pair

  - Occupies 3D space

  
• 102 and 86.5


  The bonding angle of "Seesaw" with 4BP, 1LP
• T-Shape


  A shape of a molecule:

  - 3 bonding pairs, 2 lone pairs

  - Occupies 3D space

  
• 87.5


  The bonding angle of "T-Shape"
• Octahedral


  A shape of a molecule:

  - 6 bonding pairs

  - Occupies 3D space

  
• 90


  The bonding angle of "Octahedral"
• Gas


  The only state of matter that is easily compressed
• Enthalpy


  The change of heat energy measured under a constant pressure
• Types of Crystal


  Ionic, metallic, molecular and macromolecular
• Crystals


  These are solids held together by strong and weak forces, these forces affect their melting point