The vector atom model quantizes both the magnitude and direction of electron orbits in atoms. It introduces a reference axis, such as the direction of an external magnetic field, to specify the orientation of electron orbits in space. According to this model, the direction of electron orbits is restricted to a few preferred directions determined by any external forces, like a magnetic field. Both the magnitude and direction of orbits are quantized, making the orbits vector quantities. The model also accounts for the electron spin, which is another quantized vector that contributes to the total angular momentum and magnetic moment of the atom.

1. Vector Atom Model

2. Vector Atom Model
• Concept of Spatial quantisation
• Spinning of electron

3. Spatial Quantisation
• According to quantum theory, direction or
orientation of orbits in space should be
quantised in addition to the magnitude
• To specify the orientation of electron orbit in
space, a fixed reference axis is needed
• Reference line is chosen as the direction of
external magnetic field applied to the atom
• Projections of the quantised orbits on the field
direction must be quantised

4. • The direction of electron is restricted by quantum
mechanics is called space quantisation
• The axis of orbit may point only in a few
preferred directions. These directions are
determined by the direction of any external force
that may be acting on the atom like magnetic field
• Thus according to quantum theory both
magnitude and direction of the orbits are
quantised. The introduction of such a space
quantisation make the orbits vector quantities

5. For an electron in p orbital,
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6. Spinning of electron
• Concept was introduced by Uhlenbeck and
Goudsmith in 1926
• Electron spins about its own axis and it also
moves around the nucleus of the atom
• Like the spinning of planet
• According to quantum theory,spin of electron
also should be quantised
• A new quantum number called spin quantum
number is introduced

7. • Orbital and spin motion are considered as
quantised vectors
• Atom model based on these quantised vectors
is called vector atom model
Spin endows electron with a spin angular
momentum and spin magnetic moment
Total angular momentum is the vector sum of
orbital angular momentum and spin angular
momentum
Total magnetic moment of the atom is the vector
sum of orbital and spin magnetic moments
s