Bonding and Structure

First part of unit:

IONS

You need to understand what an ion is and how it is created.

A simple introduction can be found here:

Ionic bonding

• Bonding of elements through gain or loss of electrons
• Can be represented through diagrams
• Diagrams show energy levels and the electrons circling the nucleus
• Ionic bonding is the bonding through the loss or gain of electrons.
• When an atom loses or gains one or more electrons, it becomes an Ion.
• A positive ion is called a 'cation' - this is when an atom lose electrons
• A negative ion is called a 'anion' - this is when an atom gain electrons

Covalent bonding

• Bonding of elements through the sharing of electrons to reach a stable energy level
• Can be represented through diagrams
• Diagrams show energy levels and electrons circling the nucleus
• Covalent bonding is the bonding through the sharing of electrons

Covalent substances properties...

• liquids or gases (because of weak intermolecular forces)
• low melting and boiling points
• insoluble in water
• cannot conduct electricity

Metallic bonding

• Atoms obtain a more stable electron structure in metals
• Electrons in outer energy level of atom move freely throughout structure
  • (delocalised electrons from a mobile 'sea' of electrons)
• When atoms lose electrons, they form a lattice of positive ions
• metals = positive ions in clouds of moving electrons
• Negatively charged electrons attract positive metal ions
  • Electrons bound with with ions with strong electrostatic forces of attraction