Category Archives: 1.3 Bonding

Forces between molecules

Forces between molecules: • permanent dipole–dipole forces • induced dipole–dipole (van der Waals, dispersion, London) forces • hydrogen bonding. The melting and boiling points of molecular substances are influenced by the strength of these intermolecular forces. The importance of hydrogen bonding in the low density of ice and the anomalous boiling points of compounds.       Assessment and practical opportunities Students should be

Read more

Bond polarity

Electronegativity is the tendency of an atom to attract electron density from a shared pair of electrons contained in a covalent bond. The electron distribution in a covalent bond between elements with different electronegativities will be asymmetrical. This produces a polar covalent bond, and may cause a molecule to have a permanent dipole. In general, Electronegativity increases across the periodic table– due to successive

Read more

Shapes of simple molecule and ions

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: VSEPR (valence shell electron pair repulsion) The effect of electron pair repulsion influences bond angles Students should be able to: • explain the shapes of, and bond angles

Read more

Bonding and physical properties

The four types of crystal structure: • ionic • metallic • macromolecular (giant covalent) • molecular. The structures of the following crystals as examples of these four types of crystal structure: • diamond • graphite • ice • iodine • magnesium • sodium chloride. Assessment and practical opportunities Students should be able to: • relate the melting point and conductivity of

Read more
« Older Entries