Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 1

Wave Properties

A wave is defined as a continuously repeating change or oscillation in matter or in a physical field by which energy is transmitted.

It is characterised by - its wavelength – - its frequency- its amplitude

u

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 2

Components of a Light Wave

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 3

Electromagnetic Spectrum

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 4

Photoelectric Effect

Photon absorbedPhoton's energyknocks off electronsExcess energy appearsas kinetic energy of electrons

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 5

Line Spectra of Some Elements

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 6

Bohr Orbits

Nucleus

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.

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 7

Line Spectra of Hydrogen

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 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

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 9

Electron Spin

If a charged particle spins it will create a tiny magnetic field. This is what electrons do. This spin 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.

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 10

Boundary Surface Diagram of Orbitals

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 11

Orbital Energies

Single-electron atoms Many-electron atoms

Quantum Theory and the Electronic Structure of Atoms

General Chemistry I CHM 111 Dr Erdal Onurhan Slide 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.