Zusammenfassung der Ressource
Bonding and Intermolecular forces.
- COValent bonding
- This is the sharing of
electrons, to gain a full
outer shell, between
two non-metals.
- This does not necessarily
have to form in gases,
they can also be solids
e.g. diamond.
- It is very strong so a lot
of energy is required to
break it, hence why
diamond is the
strongest object on
Earth.
- Electronegativity
- This is the ability of an atom to pull electrons
(e-) towards itself, in a covalent bond.
- Electronegativities increases as you go
across a period and as you go up a
group.
- However, noble gases are not
electronegative as they already
have a full outer shell.
- For example, in Hydrogen
Fluoride, the e-'s are tending
towards the Fluorine atom,
in the covalent bond.
- This is because Fluorine is more
electronegative than Hydrogen.
- The Fluorine is said to be
slightly negative, and the
Hydrogen, slightly positive.
- Ionic bonding
- This is the transfer of e-'s
from a metal to a non-metal.
to get a full outer shell.
- This bond is also very strong so ionic
compounds have a higher melting point.
- They usually form a cubical
structure, called a giant ionic lattice.
- The atom that loses e-'s become a positive
ion and the one that gains becomes a
negative ion.
- Opposite ions attract, forming a
lattice of ions.
- Metallic bonding
- The bonding that occurs
between positive metal ions
and delocalized electrons
- These are strong so metals have a high melting point
and can conduct electricity due to the delocalized e-'s,
which carry current.
- Metals are also malleable
because the atoms can roll over
each other without breaking the
bond.
- Van Der Waals
- This force occurs between all molecules.
- It is caused by the
movement of electrons in
molecules. As e-'s in a
molecule orbit continuously,
sometimes, the e' density is
higher on one side causing it
to be negative.
- If this happens on more than one
of the same molecule, VdW forms
by the attractions of opposite
charges.
- The bigger the molecule, the
more e-'s it will have so the
stronger the VdW.
- Dipole-dipole forces
- This force occurs between molecules
when the molecule has atoms with a
clear electronegative difference. This is
due to electrostatic attractions
- The greater the electronegative
difference, the stronger the force.
- For example, HCl.
- Molecules with
electronegative
differences are said
to be polar.
- Hydrogen bonding
- This is the strongest
force and forms
between molecules that
have Hydrogen attached
to a Fluorine, Oxygen or
Nitrogen in it.
- Water is denser than
ice because the
structure of the water
molecules in ice leaves
large gaps in between
them.
- Permanent dipoles
- This also occurs in molecules that
have atoms with different
electronegativities.
- If the molecule has more than two different atoms
and their electronegativity differences are not
symmetrical, the molecule has permanent dipole.
- For example, water has 2 Hydrogens and
one Oxygen. You need to draw the shape
of it.
- As Oxygen is more
electronegative than Hydrogen,
the shared pair of e-'s in both
covalent bonds will tend towards
the Oxygen.
- As both electronegativities are arranged
in approximately the same direction,
they are not symmetrical.
- So they a
permanent dipole
and are polar.
- Coordinate Bonding
- This is a covalent bond
where one atom donates
both electrons.
- E.g. NH3 + H+ ---- NH4