The document introduces the Linear Combination of Atomic Orbitals (LCAO) method, which was developed to overcome the inability to solve the Schrodinger equation for multi-electron systems. LCAO proposes that atomic orbitals interfere constructively and destructively to form molecular orbitals. Bonding molecular orbitals are formed through constructive interference that increases electron density between nuclei, lowering energy and stabilizing the system. Antibonding molecular orbitals occur through destructive interference, increasing electron density away from nuclei and destabilizing the system.

1. PRESENTED BY-
PRANAV.M
XI A
K. V. NO.2 KASARAGOD

2. 
 Concept introduced in Molecular orbital theory.
 to overcome the problem of being unable to solve the
Schrödinger equation for a system with more than
one electron
WHAT IS LCAO

3. 
 According to LCAO atomic orbitals interfere
constructively and destructively to form molecular
orbitals.
 If an electron can be found in an atomic orbital
belonging to atom A and also to atom B, then the
overall wave function is a superposition of the two
orbitals.
FEATURES OF LCAO

4. 
 BMO-bonding molecular orbitals are formed when
 wave functions of atomic orbitals are added-
 There occurs constructive interference of atomic
orbitals-
 Atomic orbitals overlap each other in phase.
BMO

5. 
 Electron density is located between the nuclei-
reduces repulsion between them-
reduces the energy of the molecular orbital-
stabilizes the system
The energy of BMO is always less than the participating
atomic orbitals
PROPERTIES OF BMO

6. 
 ABMO-antibonding molecular orbitals are formed
when-
 Wave functions of atomic orbitals are subtracted-
 There occurs destructive interference of atomic
orbitals-
 Atomic orbitals overlap without phase
ABMO

7.  Electron density is located far away from the two nuclei
which creates a nodal plane between the nuclei-
 Increases repulsion between them-
 Increases the energy of the system-
 Destabilizes the molecule
 The energy of ABMO is higher than that of parent
atomic orbitals.
PROPERTIES OF ABMO

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