Vector atom model

Notes

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, Magnitude of angular momentum Direction,

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