hybridisation

Some atoms form a different
number of covalent bonds
than the electron
configurations of those atoms
might suggest they should
form.
hybridisation

In general, when we look at
the electron configuration for
an atom, we can infer they
type of bonding that it will
undergo. However, certain
atoms like carbon, beryllium,
and boron, react differently
than is expected.
hybridisation

Carbon has an electron
configuration of 1s22s22p2.
That indicates that there are 4
electrons in its valence shell.
The 2s orbital is full, and there
are there are 2 half-filled porbitals.
hybridisation

The two half-filled p-orbitals
would suggest that carbon
would form two covalent
bonds. However, scientific
research proves otherwise.
hybridisation

It appears that carbon will
“promote” one of the electrons
from the 2s orbital to the 2p
orbital, leaving it with 4 halffilled orbitals. This gives
carbon the ability to form 4
covalent bonds.
hybridisation

Chemists describe this unusual
behavior as hybridisation.
Hybridisation is the
rearrangement of electrons
within the valence orbitals of
atoms during a chemical
reaction.
Hybridisation

In carbon, the four half-filled
orbitals all have identical
energies, and each is referred
to as an sp3 hybrid orbital.
3
There are a total of 4 sp
hybrid orbitals, as is illustrated
by adding the superscripts (a
1 is assumed for the s).
Hybridisation

Once hybridisation has taken
place, any one of the four is
equivalent to any other. All
four orbitals have new bond
characteristics that are
different from the
characteristics of the s and p
orbitals.
hybridisation

hybridisation also occurs in
compounds of beryllium. The
electron configuration if Be is
1s22s2. It would appear to
have no half-filled orbitals with
which to form covalent bonds.
hybridisation

However, Be can form 2
covalent bonds by “promoting”
one of the electrons in the 2s
orbital into the 2p orbital,
giving it 2 half-filled orbitals.
hybridisation

The new half-filled orbitals
formed by Be are referred to
as sp hybrid orbitals. There
are 2 sp hybrid orbitals.
hybridisation

Boron also undergoes a type
of hybridisation. The electron
configuration of B is 1s22s22p1.
Boron will promote one of the
2s electrons, giving it 3 halffilled orbitals in its valence
shell, allowing it to form 3
covalent bonds.
hybridisation

This kind of hybridisation is
referred to as sp2
hybridisation.
Metallic Bonding

Metallic atoms, which have
few valence electrons and low
ionization energies, cannot
achieve the inert gas
configuration by sharing
electrons or donating them to
other metallic atoms.
Metallic Bonding

Therefore, neither ionic nor
covalent bonding is possible
between metallic atoms.
However, a relatively strong
type of bonding, called
metallic bonding, does
occur in metals.
Metallic Bonding

Metals consist of a crystalline
lattice in which positive ions
are arranged in fixed patterns,
and the valence electrons are
free to move. These electrons
do not belong to individual
atoms, but rather to the
crystal as a whole.
Metallic Bonding

The “sea of electrons”
produces an attractive force
that fixes the positions of the
metallic ions. Because the
electrons can move about
freely, metals are good
conductors of heat and
electricity.