1:4 - Bonding Flashcards
Ionic bonding
electrons transferred
between non-metal, metal
Covalent bonding
electrons shared
between non-metal, non-metal
Each atom gives an electron to form a bond pair
Definition of Co-ordinate bonding
In co-ordinate bonding both electrons in the bond are supplied by one atom only in the covalent bond
Definition of non-polar covalent bonds
Electrons are shared equally between the two atoms
Definition of polar covalent bonds
Electrons are shared unequally between the two atoms
Definition of electronegativity
Ability of the atom in a molecule to attract the bonding pair of electrons towards itself.
Polar bonds + electronegativity
Bonding electrons are pulled towards the more electronegative atom. This atom takes up a slightly negative charge/ the other positive (delta)
Electronegativity increases. Why?
Increases across period - increase in protons and nuclear charge, shielding by inner electrons, therefore overall attraction by nucleus for bonding pair of electrons increases
Electronegativity decreases. Why?
Decreases down a group - increased shielding by inner electrons, weaker effective nuclear charge therefore weeker attraction between nucleus
Types of intermolecular forces
> dipole - dipole
induced dipole -induced dipole
Hydrogen Bonds
Intermolecular Bonding
The weak bonding holding the molecules together, and governs its physical properties
Intramolecular Bonding
The strong bonding between the atoms in the molecule and governs its chemistry
Dipole-Dipole forces
> in polar molecules - because positive and negative charge
if they arrange themselves so that the negative region is close to a positive region of another molecule there will be an attraction.
problem - not always aligned to produce an attraction due to random movements of the molecules.
Van der Waals
Induced dipole - induced dipole
> forms in non-polar bonds due to constant movement of electrons around the nuclei
sometimes more electrons are concentrated on one side of the atom - causing a temporary dipole.
Temporary dipole
> positive end pulls the negative of another molecule.
Created and destroyed all the time as electrons are in constant motion.
Hydrogen bonds
> strongest
H bonded to F,O,N (very electronegative + have lone pairs
Effects of Hydrogen bonding - Boiling Temperatures
> HIgher biling point than molecules of a similar size as Hydrogen bonds are stronger than VdW
VSEPR Theory
> Shape is governed by number of pairs in outer shell of central atom
pairs arrange themselves around central atom as far apart as possible so that repulsion is minimum
L.P - L.P > L.P - B.P > B.P - B.P
Two b.p
linear, 180
as far apart they can get
Three b.p
trigonal planar, 120
four b.p
tetrahedral, 109.5
all repel each other equally
three b.p + one l.p
trigonal pyramidal, 107
l.p - b.p repulsion is greater = forces the b.p together, slightly reducing the bond angle
two b.p + two l.p
bent/ v-shaped, 104.5
l.p - l.p repulsion forces the b.p closer and reduces the angle
five b.p
trigonal bipyramidal, 120 + right angles
six b.p
octahedral, 180
