CHEMESTRY
BONDING & STRUCTURE
WHAT HAVE WE STUDIED TILL
NOW??
• STATES OF MATTER
• KINETIC PARTICLE THEORY
• ATOMS, ELEMENTS & COMPOUNDS
BONDING
All materials are made up
of atoms. These atoms
are held together by
forces called interatomic
bonds. The bonds act like
springs, linking each atom
to its neighbor.
IONIC BONDING
• Ionic bonds occur between
metals and non metals.
• Electrons are transferred from
metal to non metal atoms
• By doing this both the atoms
become more stable by having a
complete outer shell.
DOT &
CROSS
DIAGRAM
REDOX REACTION
Oxidation
• Oxidation is defined as a process
in which an electron is removed
from a molecule during a
chemical reaction.
Reduction
• Reduction is defined as a process
in which an atom or a group of
atoms gain number of electrons
associated with them.
• Redox reaction is defined as a process in
which simultaneous oxidation and
reduction takes place.
IONIC STRUCTURE
Ionic solids are held together by
the electrostatic attraction
between the positive and
negative ions.
For example, the sodium ions
attract chloride ions and the
chloride ion attracts sodium ions.
The result is a three-dimensional
structure of alternate Na+ and
Cl– ions.
IONIC STRUCTURES
• Ionic structures are solids at room temperature and have high melting
and boiling point.
• They are usually hard substances.
• They mainly dissolve in water.
• They usually conduct electricity when in the molten state or in
aqueous solution.
• They usually cannot conduct electricity when in solid state.
IONIC STRUCTURE
LATTICE
AQUEOUS SOLUTION
• The ions in a solid ionic
compound are not randomly
arranged. Instead, they have a
regular, repeating arrangement
called an ionic lattice . The lattice
is formed because the ions
attract each other and form a
regular pattern with oppositely
charged ions next to each other.
• An aqueous solution is one in
which the solvent is liquid water.
That is, solute (dissolved) ions
and molecules are surrounded by
water molecules and
incorporated into the network of
bonds within the water.
LATTICE
This shows only a small part of a tiny
crystal of sodium chloride ions. Many
millions of sodium ions and chloride ions
would be arranged in this way in a
crystal of sodium chloride to make up the
giant ionic lattice structure. Each
sodium ion is surrounded by six chlorine
ions and each chlorine ion is surrounded
by six sodium ions.
AQUEOUS
SOLUTION
MORE ABOUT IONIC STRUCTURES
Why do they have a high melting
and boiling point????
Why do they dissolve in water to
form a aqueous solution????
=This is due to the high
electrostatic attraction between
the ions holding the crystal lattice
together. A lot of energy is
therefore needed to separate the
substance and melt it.
=this is because water molecules
are able to bond with both
positive and negative charge ions,
which breaks up the lattice and
keeps the ions apart.
Why can ionic
structures usually
conduct electricity
in molten or aqueous
state????
= The forces of attraction are weakened
when dissolved or melted . Hence they are
free to move to the appropriated
electrode. This allows current to pass
through the molten structure.
= hence solid structure are not able to
conduct electricity as they are not free to
move.
=(electrode), electric conductor, usually
metal, used as either of the two terminals
of an electrically conducting medium; it
conducts current into and out of the
medium
FORMULAE OF IONIC SUBSTANCES
• Redox reaction = in oxidation-reduction reactions electrons move
between atoms.
This is atom A and B and a electron is moving out of atom A into atom
B so this is a redox reaction.
FORMULAE OF IONIC SUBSTANCES
• Reduction = gain of electron
• Oxidation = loss of electron
it seems opposite as electrons
have a negative charge
Here atom A is being oxcidiced (losing an electron)and atom B is being
reduced (gaining a electron).
OIL RIG
OXIDATION IS LOSS
REDUCTION IS GAIN
•
•
•
•
•
•
•
3+
2+
1+
0
123-
add electrons
charge goes down
COVALENT
BONDS
Another way in which atoms
can create a stable molecule is
by sharing an electron in their
outer shell. this occurs
between non metal atoms.
During the bond formation ,
the atoms gain the stability of
the noble (inert) gas electronic
configuration .
COVALENT
STRUCTURE
Compounds containing
covalent bonds have
molecules whose
structure can be classified
as simple molecular or
gaint covalent.
SIMPLE
MOLECULAR
Simple molecular structure
are simple, formed from only
a few atoms. They have
strong covalent bonds
between the atoms within a
molecule (intramolecular
bonds) but have weak bonds
between the molecules
(intermolecular forces).
Giant
covalent
Giant covalent structure
contains many hundreds of
thousands of atoms joined by
strong covalent bonds.
Example of substances with
this type of structure are
diamond, graphite and silicon
oxide.
PROPERTIES OF COVALENT
COMPOUND
• As simple molecular compound,
they are usually gases, liquids or
solids with low melting & boiling
points.
• Generally they do not dissolve in
water. However water is an
excellent solvent and can interact
with and dissolve some covalent
molecules better than others.
Covalent structures are generally
soluble in organic solvents.
• Generally they do not conduct
electricity when molted or
dissolved in water as they do not
contain ions. Though some
molecules react with water to
form ions. Ex- hydrogen chloride
gas produces aqueous hydrogen
ions and chloride ions when it
dissolves in water.
DIFFERENT FORMS
OF CARBON
Carbon is a non metallic
element which exists in more
than one solid structural form.
These are graphite and
diamond. They exhibit
different physical properties.
The different physical
properties that they exhibit
lead to graphite and diamond
being used in different ways.
GRAPHITE
Graphite has a layer structure.
Whithin each layer every
carbon atom is bonded to
three others by strong
covalent bond. Each layer is
therefore like a gaint covalent
molecule. Between these
layers are weak attraction
forcesand so the layers will
pass over easily.
GRAPHITE
With only three covalent
bonds formed between
carbon atoms in every layer an
unbonded electron is present
on each carbon electron.
These delocalised electrons
form electron clouds between
the layers hense conducting
electricity.
DIANOMD
Each carbon atom is bonded with
four others through covalent
bond.
They form tetrahedral
arrangement similar to silicon
oxide. This bonding scheme gives
rise to a very rigid three
dimensional structure accounts
for the extreme hardness. All the
electrons of the atoms are used
to form covalent bonds so there
are no electrons to conduct
electricity.
Allotropes of
carbon
It is possible to manufacture
different allotropes of carbon.
Diamond is made by heating
graphite to 300.c under high
pressure. Graphite can be
made by heading a mixture of
coke and sand at a very high
temperature in an electric arc
furnace for about 24 hours.
METALLIC
BONDING
Another way in which atoms
obtain a more stable electronic
configuration is found in metals.
Electrons in the outer shell of the
atoms of a metal move freely
throughout the structure. They
are delocalised forming a sea of
electrons. When these metal
atoms loose electrons they form
a gaint lattice of positive atoms.
METALLIC BOND
The negatively charged
ions attract all the
positive metal electrons
and bond them together
with strong electrostatic
forces of attraction as a
single unit.
PROPERTIES OF METAL
• They conduct electricity due to
the mobile electrons within the
metal structure. When a metal is
connected in a circuit, the
electrons move toward the
positive terminal while at the
same time electrons are fed into
the other end of the metal from
the negative terminal.
• They usually have a high melting
and boiling point due to strong
attraction between the ions.
• They have very high dencity as
they are packed very closely
together.
PROPERTIES OF METAL
• They are malleable and ductile.
Unlike fixed bonds in diamond,
metal bonds are not rigid but
they are still strong. if a force is
applied to metals, rows of ions
will slide over one another. They
reposition themselves and the
strong bonds re form.
BYSAMARTH.
J