Structures of substances: molecular, ionic, covalent, metallic

Structures of substances

• There are four main substances:
• - Simple Molecular
• - Giant Ionic
• - Giant covalent
• - Giant Metallic

Structures of substances

• Simple Molecular Structures
• Small molecules containing few atoms (e.g H2O, CO2)
• Contain strong covalent bonds
• Forces between atoms are super-strong
• Forces between molecules are fairly weak
• Properties:
• Low melting point and boiling point
• Do not conduct electricity
• Tend to have little strength (soft)

Structures of substances

• Giant Ionic Structures
• - Ions held together by strong attraction
• - Forces equal in all directions in lattice
• - Tightly packed ions
• - Strong forces between ions

Structures of substances

• Ionic substances conduct electricity when they are molten because the ions are free to move around. Many can dissolved in water, where they will also conduct electricity (e.g. NaCl)
• Giant Covalent Structures:
• - Large network of bonds - giant covalent
• - Substances as: diamond, graphite and silicon dioxide
• - Held together in many strong covalent bonds
• - They are hard