1 CHAPTER 6 CHAPTER 6 ELECTRONIC STRUCTURE OF ATOMS
2 CONTENT 6.1 The wave nature of light 6.2 Quantized Energy and Photons 6.3 Bohr’s Model of the Hydrogen Atom 6.4 The Wave Behaviour of Matter 6.5 Quantum Mechanics and Atomic Orbitals 6.6 Representations of Orbitals 6.7 Orbital in Many-Electron Atoms 6.8 Electron Configurations 6.9 Electron Configurations and The Periodic Table
3 Learning Outcomes should be able to name the orbital of an electron from the n , l , m l values given Able to write the electronic configuration of any element Able to calculate the energy associated with electron movement in atom (Bohr model)
4 INTRODUCTION In the Periodic Table, elements that exhibit similar properties are placed together in the same column. E.g. i. Na and K (Group 1A) are soft reactive metals. ii. He and Ne (Group 8A) are unreactive gases. The fundamental reason for this similarity lies on the behaviour of electrons in atoms.
5 Con’t: INTRODUCTION When atoms react – it is the electrons that interact (share/transfer electron). Therefore, we must understand the behaviour of electrons. Arrangement of electrons in atom is called electronic structure (configuration) .
6 Con’t: INTRODUCTION ELECTRONIC STRUCTURE Electronic structure refers to: - No. of electrons that an atom possesses. - Electron distribution around the atom. - Electrons energies.
7 6.1 The Wave Nature of Light When you sense the warmth of a fire, you are feeling what scientists call radiation or electromagnetic radiation . Electromagnetic radiation carries energy through space and is therefore also known as radiant energy.
8 Con’t: 6.1 The Wave Nature of Light Fire gives off light (visible radiation) and heat (thermal radiation). Both types of electromagnetic radiation exist in the form of electromagnetic waves. All waves have wavelength, (lambda) and amplitude, A and frequency, (nu) characteristics.
10 Con’t: 6.1 The Wave Nature of Light Frequency The frequency (nu) of a wave is the number of cycles that pass through a given point in one second. Unit of frequency is Hertz (Hz). 1 Hz = 1 cycle per second or (1 s -1 ).
11 Con’t: 6.1 The Wave Nature of Light Wavelength The wavelength, (lambda) is the distance between successive peaks (or valleys) Unit of depends on the type of radiation.
12 Con’t: 6.1 The Wave Nature of Light Common units for Electromagnetic Radiation: unit symbol length(m) type of radiation • Angstrom Å 10 -10 x ray • nanometer nm 10 -9 UV, visible • micrometer m 10 -6 IR • milimeter mm 10 -3 IR • centimeter cm 10 -2 microwave • meter m 1 TV, radio
14 Con’t: 6.1 The Wave Nature of Light Relationship between and : = c / or c = where c is the speed of light, 3.00 10 8 ms -1 .
15 Example 1 Calculate the wavelength of an electromagnetic radiation that has a frequency of 9.22 10 17 s -1 .
- Spring '09
- Electron, Atomic orbital