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Topic notes


Summary shapes of molecules and molecular ions



Worksheets and power point presentations

Hybridization and delocalization.doc

Intermolecular forces Van der Waal's
excellent tutorial on bonding
Dissolving of ionic solid hydrogen bonding romantic hydrogen bonds more on H-bonds
More dissolving
Conductivity of ionic compounds metallic bonding ionic vs covalent
a little movie about an ionic bond
Formal charge exercises
Using formal charges to find most stable arrangement

The animation centre has many different animations which are relevant to this IB topic: Animation centre
  • formation of an ionic compound (7 of 7 is probably the most useful one)
  • formation of a covalent bond (6 of 6)
  • VSEPR theory: 1 (linear); 2 (trigonal planar), 3 (V-shaped),4 (tetrahedral), 5 (trigonal pyramidal), 6 (V-shaped), 7 (trigonal bipyramidal), 8 (see-saw), 9 (T-shaped), 10 (linear), 11/12 (octahedral) after that there are a few error messages.
  • how the shape of a molecule affects its polarity
  • hybridization: check 1 of 15 (BeCl2); 5 of 15 (CH4); 6 of 15 (NH3); 7 of 15 (H2O); 8 of 15 (C2H4); 11/12 of 15 (sigma and pi bonding - rotation)
Lewis structures
Shapes of molecules Another shape tutorial OK one more Could not resist - wikibooks: in fact the wikibooks is probably the best one Could be last one on shapes a few more examples of shapes of molecules VSEPR
Hydrogen bonding Another hydrogen bonding one
Hybridization tutorial hybridization Hybridization tutorialsigma and pi bonds
Resonance Resonance 2 tutorial on resonance

Phet animation on shapes

Polar molecules div style="position: relative; width: 300px; height: 197px;">Molecule Polarity
Click to Run


Avogadro co uk
Pauling scale and ionic character
chemguide on the number of hydrogen bonds: number of hydrogen bonds
carbon allotropes


Bonding: images of polar and non-polar molecules; there is also another flowchart at the bottom of the page.
ionic lattices


Metallic bonding:

Links to IGCSE Edexcel chemistry

Ionic compounds
1.28 describe the formation of ions by the gain or loss of electrons
1.29 understand oxidation as the loss of electrons and reduction as the gain of electrons
1.30 recall the charges of common ions in this specification
1.31 deduce the charge of anion from the electronic configuration of the atom from which the ion is formed
1.32 explain,using dot and cross diagrams, the formation of ionic compounds by electron transfer, limited to combinations of elements from Groups 1, 2, 3, and 5, 6, 7
1.33 understand ionic bonding as a strong electrostatic attraction between oppositely charged ions
1.34 understand that ionic compounds have high melting and boiling points because of strong electrostatic forces between oppositely charged ions
1.35 understand the relationship between ionic charge and the melting point and boiling point of an ionic compound
1.36 describe an ionic crystal as a giant three-dimensional lattice structure held together by the attraction between oppositely charged ions
1.37 draw a simple diagram to represent the positions of the ions in a crystal of sodium chloride ionic compounds
Covalent substances
1.38 describe the formation of a covalent bond by the sharing of a pair of electrons between two atoms
1.39 understand covalent bonding as a strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond
1.40 explain, using dot and cross diagrams,the formation of covalent compounds by electron sharing for the following substances: i hydrogen ii chlorine iii hydrogen chloride iv water v methane vi ammonia vii oxygen viii nitrogen ix carbon dioxide x ethane xi ethene
1.41 understand that substances with simple molecular structures are gases or liquids,or solids with low melting points
1.42 explain why substances with simple molecular structures have low melting points in terms of the relatively weak forces between the molecules
1.43 explain the high melting points of substances with giant covalent structures in terms of the breaking of many strong covalent bonds
1.44 draw diagrams representing the positions of the atoms in diamond and graphite
1.45 explain how the uses of diamond and graphite depend on their structures, limited to graphite as a lubricant and diamond in cutting
Metallic crystals
1.46 understand that a metal can be described as a giant structure of positive ions surrounded by a sea of delocalised electrons
1.47 explain the malleability and electrical conductivity of a metal in terms of its structure and bonding

Answers to questions