Bonding Flashcards
Ionic Bonding
Electrostatic attraction between oppositely charged ions in a lattice
Formulas of compound ions, eg sulfate, hydroxide, nitrate, carbonate and ammonium.
SO4 2-
OH-
NO3-
CO3 2-
NH4+
Co-ordinate/ (dative covalent)
Contains a shared pair of electrons with both electrons supplied by one atom.
Metallic Bonding
Attraction between delocalised electrons and positive ions arranged in a lattice
Examples of Ionic Crystal Structures as a Giant Ionic Lattice
Sodium chloride
Magnesium oxide
Examples of Structures with Covalent Bonding in a Simple Molecular
Iodine
Ice
Carbon dioxide
Water
Methane
Examples of Structures with Covalent Bonding in a Macromolecular
Diamond
Graphite
Silicon dioxide
Silicon
Examples of Metallic Bonding in a Giant Metallic Lattice
Magnesium, Sodium
Rules for Lone and Bonding Pairs in Shapes of Molecules
-Bonding pairs and lone (non-bonding) pairs of electrons as charge clouds that repel each other.
-Pairs of electrons in the outer shell of atoms arrange themselves as far apart as possible to minimise repulsion.
-Lone pair–lone pair repulsion is greater than lone pair–bond pair repulsion, which is greater than bond pair–bond pair repulsion.
Effect of electron pair repulsion on bond angles
The greater the force of repulsion between 2 pairs of e-, the further apart the electrons will be and the bigger the bond angle.
BP=2
LP=0
Linear
BP=3
LP=0
Trigonal Planar
BP=4
LP=0
Tetrahedral
BP=5
LP=0
Trigonal Bipyramidal
BP=6
LP=0
Octahedral
BP=3
LP=1
Pyramidal
BP=2
LP=2
Bent
BP=3
LP=2
Trigonal Planar
BP=4
LP=2
Square Planar
Electronegativity
The power of an atom to attract the pair of electrons in a covalent bond.
How is a permanent dipole produced?
The electron distribution in a covalent bond between elements with different electronegativities will be unsymmetrical. This produces a polar covalent bond, and may cause a molecule to have a permanent dipole.
Why do some molecules with polar bonds do not have a permanent dipole
It contains polar bonds but is symmetrical, so the polar bonds cancel out, e.g H20 and CO2
Properties of Ionic Bonding (Crystalline Solid)
-High Boiling and Melting Points- because
of giant lattice of ions with strong electrostatic forces between oppositely charged ions
-Good Solubility in Water
-SOLID- poor conductivity, ions fixed in lattice can’t move. MOLTEN- good conductivity, ions can move
Properties of Simple Molecular Structures
(mostly gases and liquids)
low melting and boiling because of weak intermolecular forces between molecules (specify type e.g van der
Waals/hydrogen bond)
-Poor Solubility in water
-SOLID- Poor Conductor, as no ions to conduct and electrons are localised. MOLTEN- no ions
Properties of Macromolecular
(Solids)
High Melting and Boiling Point because of many strong covalent bonds in macromolecular structure. Requires a lot of energy to overcome the many strong bonds.
-INSOLUBLE in water
-Conductivity in diamond and sand: poor, because electrons can’t move (localised) graphite: good as free delocalised electrons between layers carry a current, MOLTEN- poor conductivity
Properties of Metallic Structure (Shiny Metals)
-Malleable, +ions in the lattice are all identical, planes of ions can easily slide over one another
-attractive forces in the lattice are all the same
-High Melting and Boiling Points- strong electrostatic forces between positive ions and a sea of delocalised electrons
-Insoluble in water
-SOLID: good conductivity due to delocalised e- which can move through the structure, MOLTEN: good conductor
