Thursday, October 29, 2015 Miss Stephens (ES) 1 Properties of solids Bonding Melting Point ConductivitySolubilityHardness

Thursday, October 29, Bonding Molecular Solid –Atoms covalently bonded in molecules Molecules held by weak intermolecular forces Metallic Solid –Metallic atoms in 3D lattice surrounded by loosely held valence electrons (Non-directional bond) Ionic Solid –Lattice of positive and negative ions Held together by strong electrostatic attraction Covalent Network Solid –Large lattice of very strong covalent bonds

Thursday, October 29, MELTING Point Molecular Solid –Low – most gas or liquid at room temperature Due to weak intermolecular forces Metallic Solid –Varies – Most have high (~ o C) All solids at room temperature (except mercury) Ionic Solid –High, large amounts of energy to break strong ionic bond (~1000 o C) All solids at room temperature Covalent Network Solid –Extremely high – extreme amounts of energy required (+3000 o C) All solids well beyond room temperature

Thursday, October 29, Conductivity Molecular Solid –Don’t conduct – No charged particles present Metallic Solid –Conduct very well – Charged particles free to move Loosely held electrons can move inside structure Ionic Solid –Solids don’t conduct – Charged particles can’t move –Dissolved or molten can conduct – ions can move freely Covalent Network Solid –Don’t conduct – No charged particles present in structure Except Graphite – free electrons between layers

Thursday, October 29, Solubility Molecular Solid –Polar molecular substances generally are soluble in polar solvents –Non-Polar molecular substances are soluble in non-polar solvents Metallic Solid –Not soluble in any solvent – bond not broken by attraction of solvent Metals do react with water though giving OH - and H 2 Ionic Solid –Many soluble in water Strong attraction between polar H2O & charged ions break ionic bond Covalent Network Solid –Not soluble in any solvent –covalent bond too strong