Bonding & Structure K Warne

TYPES OF STRUCTURE NetworkMolecularIonicMetallic Particles Bonding Structure Properties Examples AFTER WORKING THROUGH THIS PRESENTATION YOU SHOULD BE ABLE TO CLASSIFY THE SOLIDS BELOW ACCORDING TO THE TYPES OF STRUCTURE GIVEN IN THIS TABLE: IODINE SALT IRON CARBON (DIAMOND & GRAPHITE) ICE GLASS/SAND (SILICON DIOXIDE) IF YOU UNDERSTAND THE CONTENT YOU SHOULD BE ABLE TO PREDICT THE BONDING AND STRUCTURE IN: PLASTIC SUGAR BICARBONATE OF SODA

Giant Molecules - Network solids Strong covalent bonds Network solids have strong bonds between all atoms. The structure is extended in three dimensions. Extensive bonding and a GIANT STRUCTURE ensure the substance has high boiling and melting points are insoluble, electrons are held in bonds and generally not free to conduct electricity.

Strong covalent bonds Diamond Graphite Delocalised electrons - Weaker van der waals forces between the layers Network Solids Diamond Graphite - conducts electricity as the delocalised electrons are free to move.

Molecular solids Ice Iodine Strong covalent bonds Weaker intermolecular bonds SIMPLE MOLECULAR STRUCTURES

Microscopy FURTHER READING: Investigate how the structure of molecules is determined from x- ray diffraction patterns.

Metals (Delocalised electrons) Strong electromagnetic attraction between ions and ‘sea’ of delocalised electrons. GIANT structure – extensive strong bonding in 3 dimensions and extended structure High melting points & boiling points, good conductors of electricity, insoluble

Ionic Solids Ionic bonds An extended lattice (Regular 3D arrangement) of positive and negative ions. Strong bonding throughout ensures the structure has VERY high melting points but is soluble in polar solvents and conduct electricity when dissolved or in liquid form.

TYPES OF STRUCTURE (Solids) NetworkMolecularIonicMetallic ParticlesATOMSMOLECULESIONS +IONS & DELOCALISED e - Bonding COVALENT BONDS INTERMOLECU LAR FORCES & (COVALENT BONDS) IONIC BONDS METALLIC BONDS Structure GIANT MOLECULES SIMPLE MOLECULUL AR GIANT IONIC LATTICE METALLIC LATTICE Properties Very high Mp Bp Very high Mp Bp Insulators Insulators Insoluble Insoluble Hard Hard Low MpBp Low MpBp Insulators Insulators Soluble (Npolar) Soluble (Npolar) Brittle Brittle Very High Mp Bp Very High Mp Bp Conduct in Sol or liq Conduct in Sol or liq Soluble (Polar S) Soluble (Polar S) Brittle crystals – can be cleaved Brittle crystals – can be cleaved High mp bp High mp bp Good conductors Good conductors Insoluble Insoluble malleable ductile malleable ductile Examples Diamond Graphitef Iodine, Ice, plastic, sugar Salt, bicarbonate of soda Iron copper etc.