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Ionic Bond- the result of the electron transfer leading to attracting
between oppositely charged ions (mostly giant molecules)
o Held together by strong electrostatic forces operating in all three
dimensions
 Non-volatile (don’t evaporate quickly)
 High MP and BP
 Solids at room temperature and pressure
 Hard, brittle
o Cannot conduct a current in either solution or in the molten
state= freely moving ions
o Cannot conduct a current as a solid
o Most are insoluble in solvents, except water, because there is an
interaction between ions and the polar water molecules (iondipole interaction)- dissociates in water
o If the forces between the ions are very strong, then the ionic
substance will not dissolve in water
Covalent Bond- the electrostatic attraction between a pair of
electrons and positively charged nuclei (mostly discrete molecules, but
some are giant, such as SiO2)
o Giant covalent (aka network covalent)- macromolecular
structure, crystal structure (ex
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g
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3333 bond order
 Has a lower density than diamond
 Can conduct a current via the delocalized electrons
between layers
Fullerenes
 Spherical molecules
 Mae up of five- and six- membered carbon rings
 Sp2 hybridised carbon atoms
 Little delocalization because of the spherical (bent) shapenot planar
 Molecular, not giant
 Will dissolve in nonpolar solvents
 Low MP
 Strange compressibility properties
Electrical conductivity: diamond is less than fullerenes, which is
less than graphite
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Metallic Bond- the electrostatic attraction between a lattice of
positive ions and delocalized electrons (low electronegativities)
o Close-packed lattice- lattice of positive ions filled by a mobile
“sea” of valence electrons
o “sea” of electrons
 No valence electron belongs to any particular atom
 Free to move throughout the metal
 Conduct a current
 Interaction with light produces lustre
 Malleability
 Ductility
 Atoms are positively charge (cations)
 The attraction of these cations for the mobile
elections provides the force which holds the
structure together
o Malleability and ductility- the layers of ions can slide past each
other without breaking bonds
o Bond strength depends upon…
 Number of valence electrons
 Distance from the positively charged nucleus
o In most cases, metallic bonding is strong
 Solid is hard, though still malleable, and has a high MP and
BP
 Exceptions: Mercury and Sodium
o Alloys- metals containing more than one type of atom
 Brass (copper and zinc)
 Mercury (forms a wide range alloys called amalgams)
 Generally retain metallic properties though…
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Geometry (shape)

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Molecular shape is determined by repulsion between the valence
electron pairs
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5 of the number of bonded electrons]
If a compound has ___ electron domains and ___ non-bonding
electron pairs, then its electronic geometry is ____ and its molecular
geometry is ___
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o 4, 0, tetrahedral, tetrahedral, 109
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5
o 2,0, linear, linear, 180
o 3, 0, trigonal planar, trigonal planar, 120
o 3, 1, trigonal planar, V-shaped/angular, 117
o 5, 0, trigonal bipyramidal, trigonal bipyramidal, equatorial: 120,
axis: 90
o 5, 1, trigonal bipyramidal, saw horse/seesaw, 90 and 117
o 5, 2, trigonal bipyramidal, T-shaped, 90
o 5, 3, trigonal bipyramidal, linear, 180
o 6, 0, octahedral, octahedral, 90
o 6, 1, octahedral, square pyramidal, 88
o 6, 2, octahedral, square planar, 90
Polar bond- unequal sharing of electrons
o The greater the difference in electronegativities, the more
polar the bond
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tape, glue, etc
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Hydrogen bonding is also of great biological purpose (basis for base
pairing in DNA)
Hybrid- has characteristics of electrons in an “s” sublevel and a “p”
sublevel
o Creates an “sp” sublevel
 One of the s-electrons is promoted to the vacant p-orbital
o The total energy has not changed, just redistributed
o When atoms join together to form molecules, their outer atomic
orbitals interact with each other to produce molecular orbitals
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Pi bonds
o Formed by the “side on” interaction of electrons in p-orbitals
o Low electron density on the inter-nuclear axis, but regions of
high electron density on opposite sides of it
o Weaker than sigma bonds
o Double bonds are always one sigma bond and one pi
bond
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Single bonds are the most stable, have the lowest energy, and have
the longest bond length
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o Are not likely to occur
o Look at benzene
Resonance hybrid
o the species that actually exists when there are two or more
equivalent structures
o less energy, which means that it is more stable than any of the
resonance structures
Resonance energy- the difference in stability between a resonance
structure and the hybrid (aka delocalization energy and stabilization
energy)
Delocalised pi bond
o Allows the pi electrons to spread over more than two nuclei
o Gives the species a lower potential energy
o Makes it more stable
o Overlap of p-orbitals
Bond order- the average of the number of bonds of the different
resonance structures
Physical properties- depends primarily on the forces between the
particles
Bond strength

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o The stronger the bond…
 The harder the substance
 The higher the MP and BP
o Impurities can disrupt the “regular lattice” which weakens the
bonding
Electrical conductivity- Does the substance contain freely moving
electrically charged particles? (electrons and ions)
Solubility Rules
o All nitrates are soluble (NO31-)
o All sodium, potassium, and ammonium (NH41+) compounds are
soluble
o All sulphates (sulfates) are soluble except: Ba, Pb (II); calcium is
sparingly
o All chlorides, bromides, and iodides are soluble except those of
liver
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o All other compounds are insoluble; though some, such as Ba
(OH)2 and Ca(OH)2 are sparingly soluble



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