AP Chemistry Unit 3

molecular solids

molecular solids

at each lattice point: a molecule

held together by: IM forces

properties: low melting points, insulators (do not conduct heat/electricity well)

ionic solids

at each lattice point: an ion

held together by: ionic bonds

properties: high melting/boiling points, brittle, conduct electricity when dissolved/molten

nonbonding solids (atomic)

at each lattice point: noble gas atom

held together by: london dispersion forces

properties: very low melting point

metallic solids (atomic)

at each lattice point: a metal ion

held together by: sea of electrons

properties: high melting point, conductive, malleable

network covalent solids (atomic)

at each lattice point: nonmetal or metalloid atom

held together by: covalent bonds

properties: very high melting point

network covalent solids of carbon: diamond

each carbon atom is covalently bonded to 4 other carbons (sp3 hybridized, STRONG)

network covalent solids of carbon: graphite

each carbon atom is covalently bonded to 3 other carbons (sp2 hybridized, flat trigonal planar layers, conducts electricity)

dipole-dipole forces

exist between polar molecules

the partially + side of one polar molecule is attracted the partially - side of another polar molecule

larger EN difference = more polar = stronger d-d forces

hydrogen bonding

strongest IM force (much weaker than a covalent bond)

a hydrogen atom that is directly bonded to N O or F interacts with a lone pair on N O or F on a different molecule

more regions where H bonding is possible = stronger H bonds

london dispersion forces

caused by random electron movements

instantaneous dipole (molecules are polar for just a moment)

polarizability = the size of the electron cloud

more electrons = more polarizable = stronger london dispersion forces