1.3 bonding Flashcards
molecular bp
low, weak intermolecular forces and vdw
macromolecular bp
high, many strong covalent bonds, lots of energy needed
molecular solubility
generally poor
macromolecular conductivity when solid
only graphite, delocalised electrons between layers
when is ionic bonding stronger
ions are smaller or charge is higher
examples of dative covalent bonding/co-ordinate bond
NH4+, H3O+
how to draw a co-ordinate bond
arrow from lone pair to electron deficient atom
3 factors that affect the strength of metallic bonds
protons, delocalised electrons per atom, size of ion
linear
2:0, 180, CO2
trigonal planar
3:0, 120, AlCl3
tetrahedral
4:0, 109.5, SiCl4
pyramidal
3:1, 107, NCl3
bent
2:2, 104.5, SCl2
trigonal bipyramidal
5:0, 120/90, PCl5
octahedral
6:0, 90, SF6
electronegativity definition
the relative tendency of an atom in a covalent bond in a molecule to attract electron in a covalent bond towards itself
EN across periods and down groups
increase across period, decrease down group
polar covalent bond
unequal distribution of electrons in a bond produces a charge separation (dipole)
VDW do not occur..
in ionic substances
induced dipoles
eelctrons constantly moving, distribution changes, induced on neighbouring molecules
increasing bp of halogens
increased electrons= increased vdw
permanent dipoles
between polar molecules, significant difference in electronegativity
hydrogen bond
hydrogen atom bonded to F/N/O, must be a lone pair (in addition to vdw)
H2O/NH3/HF very high bp (anonymously)
due to hydrogen bonding
