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Intermolecular Forces and Physical Properties. Chemistry Unit 6. Non-Polar Covalent Compounds. Examples : O 2 , CH 4 , CO 2 Types of particles: 2 or more non-metals IMF’s = Dispersion Physical state – can be s, l, or g – depends on molecular weight (MW)
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Intermolecular Forces andPhysical Properties Chemistry Unit 6
Non-Polar Covalent Compounds • Examples: O2, CH4, CO2 • Types of particles: 2 or more non-metals • IMF’s = Dispersion • Physical state – can be s, l, or g – depends on molecular weight (MW) • Melting/Boiling Pts. – very low to low • Solubility in water – Not soluble • Conductivity – poor to non conducting.
Polar Covalent Compounds • Examples: H2S, HCl, H2O • Types of particles: usually 2 or more non-metals • IMF’s = Dipole-Dipole and maybe hydrogen bonds • Physical state – can be s, l, or g – depends on molecular weight (MW) • Melting/Boiling Pts. – low to medium • Solubility in water – most are soluble • Conductivity – Do not conduct.
Ionic Compounds • Examples: NaCl, MgO • Types of particles: Metal and Non-metal • IMF’s = Ionic bonds • Physical state – crystalline solids, brittle • Melting/Boiling Pts. – very high • Solubility in water – most are soluble • Conductivity – conduct as liquids or when dissolved in water..
Metallic • Examples: Al, Cu, Fe • Types of particles: cations in sea of electrons • IMF’s = metallic bonds • Physical state – all solids except Hg • Melting/Boiling Pts. – variable – depends on charge and size • Solubility in water – Not soluble • Conductivity – conduct as solids or liquids
Covalent Network Compounds Some covalently bonded substances DO NOT form discrete molecules. Graphite, a network of covalently bonded carbon atoms Diamond, a network of covalently bonded carbon atoms
Network Covalent Solids • Network solids– solids in which all the atoms are covalently bonded to each other • Network solids melt at very high temperatures, or not at all (decomposes) • Diamond does not really melt, but vaporizes to a gas at 3500 oC and beyond • SiC, used in grinding, has a melting point of about 2700 oC
Network Covalent • Examples: Carbon, Silicon, SiO2, C60 • Types of particles: usually single atoms • IMF’s = covalent bonds • Physical state – solids • Melting/Boiling Pts. – very high • Solubility in water – Not soluble • Conductivity – poor to non conducting.
Diamond vs. Graphite • Different properties due to how it is bonded. • Diamond – very hard, high mp- carbons 4 bonds each • Graphite – soft solid –carbons have 3 bonds
Allotropes of Carbon • Allotropes of carbon Link
Types of Molecular Solids Covalent Molecular (H2O) Covalent Network (SiO2 - quartz) Amorphous (SiO2 - glass)