1. Wave Properties • A wave is defined as a continuously repeating change or oscillation in matteror in a physical fieldby which energy is transmitted. • It is characterised by • its wavelength – • its frequency • its amplitude

2. Components of a Light Wave

3. Electromagnetic Spectrum

4. Photoelectric Effect

5. Line Spectra of Some Elements

6. Bohr Orbits According to the Bohr Theory, the electron in a hydrogen atom can only be found in one of these orbits. Each orbit has a specific energy value.

7. Line Spectra of Hydrogen

8. Electron Density Distribution Dot density represents electron density. Regions of high electron density represent a high probability of finding the electron in that region

9. Electron Spin If a charged particle spins it will create a tiny magnetic field. This is what electrons do. Thisspin creates a split in atomic spectra of atoms. In 1924, it was proved that electrons do spin. It was observed that there is a 50-50 distribution of spin, i.e. 50% of electrons spin in a clockwise manner, and the other 50% in an anticlockwise manner.

10. Boundary Surface Diagram of Orbitals

11. Orbital Energies Single-electron atoms Many-electron atoms

12. The Aufbau Principle Using this diagram, we can distribute electrons among orbitals in an atom. Remember that there might be exceptions in rare instances.