Bonding Flashcards
Ionic bonding
Involves electrostatic attraction between oppositely charged ions in a lattice
Ionic formulas
Positive cation-metal, no name change
Negative anion-non metal, name change
Metallic bonding
Involves attraction between delocalised electrons and positive ions arranged in a lattice
Metal properties
Good conductors-delocalised electrons
Strong, malleable, ductile, high melting points
What does strength of metsllic bond depend on
The size and charge of the ion
Covalent bonds
Metal and non metal react to share electrons and attain full outer shells
Nucleinof each atombattracted to shared electron pair
What covalent bonds are strongest
1pair-longest and weakest
3 pairs-shortest and strongest
Dative covalent bond
A covalent bond in which both ekectrons come from the same atom
- drawn with arrow in direction of electron movement not line
How to work out shape of molecules
Central atom Group/ outer electron number Charge Bonds Total Divide by 2=number of electron pairs Structure Look at 6 and 4 to wirk out lone pairs Shape Bond angle
Pair repulsion theory
Outer shell electron pairs arrange as far apart as possible to minimise repulsion
Lone pair-lone pair=greatest repulsion
Bond pair-bond pair=least repulsion
Form of electron pairs
As charge clouds that repel each other
Molecular shapes
Linear-180• Trigonal planar-120• Tetrahedral-109.5 Trigonal bipyrimidal-120/90• Octahedral-90•
Electronegativity
The power of an atom to attract the pair of electrons in a covalent bond
Electronegativity patterns
Increases accross period
Decreases down group
Factors affecting electronegativity
Nuclear charge-more protons=stonger bp nucleus attraction
Atomic radius-closer bonding electrons,stronger attraction
Shielding-less shells shielding bp, sttonger force
Polar covalent bonds
2 atoms in covalent bond have different electronegativity
2 electrons not shared equally
More e is d-, less e is d+
Non polar covalent bond
2 atoms in covalent bond have same electronegativity
2 atoms shared equally
Weakest to strongest IMF
Van der waals-weakest
Dipole dipole
Hydrogen-strongest
VDW(induced dipole dipole)
More e at one end of atom by chance at 1 moment, w slight d-/+
This makes an instantaneous dipole and weak force of attraction between 2 neighbouring oppositely charged ends of temporary dipoles
Vdw always exist
Dipole-dipole (permanent)
Bond between polar molecules, attractive force between dipoles on different molecules
Permanent so stronger than VDW
Dipole moment
Some covalent bonds are polarso arramgenent can result in molecule iverall becoming polar
Hydrogen bonding elements
Nitrogen
Oxygen
Fluorine
Shape of covalent to H bond
Linear
H bonds
H bonded to v electronegative atom
Strong intermolecular force not bond
Polar bond leaves H nucleus exposed as only one electron so strong attraction between exposed nucleus and lone pair on NOF
Crystal structures
Ionic
Metallic
Giant covalent
Molecular
Crystal structure examples
Diamond Graphite Ice Iodine Magnesium Sodium chloride
Clear ice explanation
Clear as light oasses through middle of hexagonal structure
