Bonding Flashcards
Ionice Bonding
strong electrostatic forces between oppositely charged ions
loss or gain or electrons
3D giant ionic lattice
Melting and Boiling poitns in ionic
very high
very strong electrostatic forces to break
Condutivity of Ionics
solids do not conduct but they do when they are molten or in solution as the ions are free to move
Covalent Bonding
sharing a pair of electrons
Co ordinate bond
formed between lone pairs of electrons and a H+ ion
both electron come from the same atom
2 types of covalent bonds
macro molecular
simple molecular
Macro Molecular mp and bp
very high as alot of energy is needed to break the string covalent bonds
simple molecular mp and bp
very low as you do not break the strong covalent bonds themselves but you break the weak intermolecular forces between them which does not require a lot of energy
Metalic Bonding
cations in a sea of delocalised electrons
metal atoms detached from their outer electrons
Conductivity of metals
very good conductors on either state as the energy is carried by the delocalised electrons
Malleable
can be beaten into shape easily without having to be broken
Sliding
layers of cations ‘slide’ over each other while still bonded by the elcetrons
sliding can occur in all dimensions
Down the Metal Group melting point
decreases
same number of delocalised electrons but cation gets larger
less attraction to so easily lost
Across a Metal Period melting point
increases
number of delocalised electrons increases
charge increases
stroner attraction so harder to remove
Across Metal Period conductivity
increases
more delcoalised electrons
more charge to carry energy
Polar Covalent Bond
occurs when electron pairs are shared unevenly
due to electronegativity
Electron pull in PCB
towards the more electronegativity
away from the less electronegativ atom
Partial Charge
Delta Positive
Delta Negative
Dipole
molecule which is still neutral but contains partial charge that cancel out each other
Dipole Dipole
stronger attrcation between neighboruing molecules which also contain partial charges
Melting and Boiling Point of PCB
higher than expected
Solubility in Water of PCB
Increased solubility
Elcetronegativity
Ability of an atom to attract a pair of electrons in a covalent bond
increases
across periods
decreases
up groups
Nuclear Charge
more protons
stronger attraction between nucleus and bodning pair of electrons
Aromic Radius
closer to the nucleus
stronger attraction between nucleus and bonding pair of electrons
Shielding
less shells of electrons between the nucleus and the electrons
less shielding (less repulsion)
stronger attraction between nucleus and bonding pair of electrons
Down a group Electronegativity
decreases
atomic radius increases
more shielding
less attraction between nucleus and bonding pair of electrons
Across a period Electronegativity
increases
atomic radius decreases
more nuclear charge
stronger attraction between nucleus and bonding pair of electrons
No Difference in Electronegativity
non polar covalent bond
<0.5 electronegativity
covalent bond
0.5<1.7 electronegativity
polar covalent bond
> 1.7 electronegativity
ionic bond
both electrongeativites <1.5
metalic bonding
Intermolecular Forces
weak electrostatic forces of attraction between neighbouring molecules
3 types of intermolecular forces
Hydrogen Bonding
Dipole-Dipole forces
Van de Walls forces
Hydrogen Bonding
only between
Flourine, Oxygen, Nitrogen
deshielding the Hydrogen
making it slightly positive (delta positive)
attarction betweena lone pair on NOF and a deshielded hydrogen
In Liquids Hydrogen Bonds
are continuosly breaking and reforming
In Solids Hydrogen Bonds
are permanent
In Gases Hydrogen Bonds
are completly broken
As Electronegativity decreases Hydrogen Bond Strength
decreases
Dipole Dipole Forces
uneven electron disribution
differences in electronegativity
Permanet dipole causes
a permenant dipole in a neighbouring molecule
Van De Waal Forces
weakest intermolecular force
atoms donate elctrons to the cloud
leading to a momentary tempory dipole
when do Van De Waals occur
only happen when the other 2 intermolecular forces are not present
can occur when there is dipole dipole but they are disregarded
VDW get stronger
as the number of electrons in the molecule increases
Boiling Points of Noble Gases down the group
Increase
as electron shells are added
starigh chain molecules
stronger van de waals forces
molecules can get closer
branched chain molecules
weaker van de walls forces
molecules are less close
