Chapter 2
Structure, Bonding and Properties
Keywords
Stable
A full outer shell of
electrons
Shell
A ‘layer’ of electrons
Ion
An atom that has lost or
gained electrons
Delocalised
Free to move around the
system
Oxidation
Loss of electrons
Forming Bonds
All atoms want a full outer shell of electrons. This
is a stable state. They achieve this by forming
chemical bonds with other atoms. (all need 8,
except H & He that want 2).
Ionisation (Forming ions)
Oxidation is Loss,
Reduction is Gain
(OILRIG)
Metals always form
positive ions. A group 2 metal forms a 2+ ion (loses
two electrons)
Reduction
Gain of electrons
Non-metals form negative ions.
Electrostatic force
The force between positive
and negative charges
Ionic Bonding
Delocalised
Free to move around the
system
Lattice
3D arrangement of atoms/
ions
Strong, electrostatic forces
hold ions of opposing charges
together.
The structure is described as an
ionic lattice.
The compounds have very high melting points
because of this.
Giant Covalent
These compounds are solid at room temperature. All of the atoms in a giant
covalent structure are held together by strong covalent bonds. These bonds have
to be broken, by large amounts of energy, to melt or boil these substances.
Covalent Bonding
Metallic Bonding
Non-metal atoms bond by sharing electrons to form
a very strong covalent bond.
Positive ions held together by a
“sea of delocalised electrons” from
the outer shells of the metal
atoms.
The strong electrostatic forces
between the ions and electrons mean metals have very
high melting points.
Hydrogen starts with 1 electron each, but both
need 2 electrons for a full shell.
By sharing one electron each with oxygen, they
form a single covalent bond. Oxygen shares one
electron back with each of them, so they all can
achieve a full outer shell.
Straight Lines
Most common way to represent covalent bonds,
with each line representing a
shared pair of electrons.
Metals are malleable. This means the
regular layers can slide over each other if
they are hammered.
e.g. Hydrogen gas → H-H
e.g. Water → H-O-H
Polymers
Metals/Alloys
Polymers are large molecules, made of ‘repeating units’
called monomers. All atoms are bonded to other atoms,
and they make a chain of strong covalent bonds.
Pure metals are too soft for many uses. An alloy is a
mixture of a metal with another element(s), and
these have different properties to the metals that
are in them.
Alloys are less malleable than pure metals as they
have irregular layers, and so they cannot slide over
each other as easily. The atoms are still held
together by metallic bonding.
In graphite, only 3 electrons from each carbon atom
form strong covalent bonds, leaving one delocalised
electron per atom.
Graphite has a high melting point, and is a good
thermal/electrical conductor.
Diamond is made up of carbon forming four covalent bonds.
Graphite is made of hexagonal rings of carbon, each atom forming three bonds.
Graphene is a single layer of graphite, and is used to form nanotubes/fullerenes.
States of Matter
The free electrons are able to move so metals are good
conductors of electricity and heat.
Nanoparticles
Limitations of the particle model:
•
there are no forces shown between spheres
•
all particles are represented by spheres
•
spheres are represented as solid and inelastic
Between 1 and 100 nm in size.
Silver - Clothes/deodorant as antibacterial
Titanium dioxide - Sunscreens as anti-UV
Medicine - Drugs designed to work on one type
of cell only
© Making Solutions 2018
www.revisechemistry.co.uk
On the left, the intermolecular forces are much weaker, so chains can
move over each other. To increase the rigidity (and boiling point) we
can add cross-links as shown on the right.
Addition polymers are made from one monomer that
contains at least one double bond (normally an alkene).
Condensation polymers are made from at least two
monomers, and make water too.
Simple Covalent
These have strong covalent
bonds within the molecule, but
weak intermolecular forces of
attraction. This means they are
either gas or liquid at room
temperature.
They do not conduct electricity as there are no free
electrons.
Nanoparticles have a large surface area, because of how small
their individual volumes are.
Chapter 2
Structure, Bonding and Properties
Keywords
Stable
A full outer shell of
electrons
Covalent Bonding
Metallic Bonding
Draw a dot and cross diagram for water. (H2O)
Draw a diagram to show how metals are held together, and
describe the bonding.
Forming Bonds
Why do atoms form bonds?
Shell
A ‘layer’ of electrons
Ion
An atom that has lost or
gained electrons
Ionisation (Forming ions)
Draw the electronic structure of an atom of
aluminium and its ion.
Ionic Bonding
Draw a dot and cross diagram for potassium
chloride.
Describe the type of bonding.
Delocalised
Free to move around the
system
Polymers
Oxidation
Loss of electrons
Reduction
Gain of electrons
Electrostatic force
The force between positive
and negative charges
Draw a diagram of two different polymers, labelling them
with information about properties.
Metals/Alloys
Why do we use alloys for building materials, rather
than pure metals? Give comparative information on
structure and bonding. A diagram may help you.
Delocalised
Free to move around the
system
Lattice
3D arrangement of atoms/
ions
Describe the two types of polymerisation
States of Matter
Giant Covalent
Complete, and fill, the diagram below
Why are giant covalent compounds
solids at room temperature?
Simple Covalent
Explain why simple molecules have low
melting points, and why they can’t
conduct electricity.
Nanoparticles
Define nanoparticle, give two examples, and state why they
have a large surface area
Describe their structure and bonding of
diamond and graphite.
What are the limitations of the particle model?
© Making Solutions 2018
www.revisechemistry.co.uk
Chapter 2
Structure, Bonding and Properties
Keywords
Stable
A full outer shell of
electrons
Covalent Bonding
Metallic Bonding
Draw a dot and cross diagram for water. (H2O)
Draw a diagram to show how metals are held together, and
describe the bonding.
Forming Bonds
Why do atoms form bonds?
To achieve a full outer shell of electrons
Shell
A ‘layer’ of electrons
Ion
An atom that has lost or
gained electrons
Ionisation (Forming ions)
Draw the electronic structure of an atom of
aluminium and its ion.
Ionic Bonding
Draw a dot and cross diagram for potassium
chloride.
Describe the type of bonding.
Delocalised
Free to move around the
system
Polymers
Oxidation
Loss of electrons
Reduction
Gain of electrons
Draw a diagram of two different polymers, labelling them
with information about properties.
Metals/Alloys
Electrostatic force
The force between positive
and negative charges
Why do we use alloys for building materials, rather
than pure metals? Give comparative information on
structure and bonding. A diagram may help you.
Delocalised
Free to move around the
system
Pure metals are too soft for many uses. Regular
layers of atoms just slide over each other.
Alloys are less malleable than pure metals as they
have irregular layers, and so they cannot slide over
each other as easily.
Lattice
3D arrangement of atoms/
ions
K+
ion
Giant Covalent
Complete, and fill, the diagram below
Why are giant covalent compounds
solids at room temperature?
gas
solid
What are the limitations of the particle model?
•
•
•
there are no forces shown between
spheres
all particles are represented by spheres
spheres are represented as solid and
inelastic
Clion
Electrostatic forces of attraction between
positive and negative ions.
States of Matter
liquid
Strong electrostatic forces between the positive metal
ions and negative electrons
the left, the intermolecular forces are much weaker,
so chains can move over each other. To increase the
rigidity (and boiling point) we can add cross-links as
shown on the right.
Describe the two types of polymerisation
Addition polymers are made from one monomer that
contains at least one double bond (normally an alkene).
Simple Covalent
Explain why simple molecules have low
melting points, and why they can’t
conduct electricity.
All of the atoms in a giant covalent structure
are held together by strong covalent bonds.
These bonds have to be broken, by large
amounts of energy, to melt or boil these
substances.
Describe their structure and bonding of
diamond and graphite.
Weak intermolecular forces of attraction.
Doesn’t take much energy to break these
forces.
They do not conduct electricity as there
are no free electrons.
Diamond - Each carbon covalently bonded to
four other carbons
Graphite - Each carbon covalently bonded to 3
others, free moving electrons
© Making Solutions 2018
www.revisechemistry.co.uk
Condensation polymers are made from at least two
monomers, and make water too.
Nanoparticles
Define nanoparticle, give two examples, and state why they
have a large surface area
Between 1 and 100 nm in size.
Silver - Clothes/deodorant as antibacterial
Titanium dioxide - Sunscreens as anti-UV
Medicine - Drugs designed to work on one type of cell only
Nanoparticles have a large surface area, because of how
small their individual volumes are.