1 RJC Orbital Theory The space around a nucleus in which an electron is most likely to be found is called an orbital. The space around a nucleus in which an electron is most likely to be found is called an orbital. orbital nucleus

2 RJC What does an orbital look like? The further the electrons are from the nucleus the higher in energy is the orbital. The further the electrons are from the nucleus the higher in energy is the orbital

3 RJC What does an orbital look like? The shape of orbitals varies with energy. The shape of orbitals varies with energy. s orbital p orbital

4 RJC The 1s Orbital The lowest energy electrons occupy the spherical 1s orbital. The lowest energy electrons occupy the spherical 1s orbital. 1s orbital

5 RJC The 2s Orbital The spherical 2s orbital is higher in energy than the 1s orbital. The spherical 2s orbital is higher in energy than the 1s orbital. 2s orbital

6 RJC The 2p Orbitals Three “dumb bell” shaped 2p orbitals of equal energy occupy different spatial co-ordinates. Three “dumb bell” shaped 2p orbitals of equal energy occupy different spatial co-ordinates. 2p x orbital 2p y orbital 2p z orbital

7 RJC The 3s, 3p, 4s and 4p orbitals... 2p y 3p y 4p y 2s 3s 4s

8 RJC Orbitals : Organic Chemistry The chemistry of carbon is mainly concerned with bonds between the 1s, 2s and 2p orbitals. The chemistry of carbon is mainly concerned with bonds between the 1s, 2s and 2p orbitals. 2s 2p x + 2p y + 2p z 1s

9 RJC The Electronic Configuration Describes the orbitals occupied by electrons, for a given element. Describes the orbitals occupied by electrons, for a given element. carbon

10 RJC The Ground State Electronic Configuration Describes the lowest energy Electronic Configuration. Describes the lowest energy Electronic Configuration. carbon

11 RJC Rules for placing electrons in orbitals... Electrons do NOT randomly occupy orbitals... Electrons do NOT randomly occupy orbitals... The Aufbau Principle Pauli Exclusion Principle Hund’s Rule

12 RJC The Aufbau Principle Always begin by filling the lowest energy orbitals first! Always begin by filling the lowest energy orbitals first! carbon

13 RJC Pauli Exclusion Principle Only two electrons can be placed in each orbital and they must be of opposite spin. Only two electrons can be placed in each orbital and they must be of opposite spin. carbon

14 RJC Hund's Rule...given two or more orbitals of equal energy...given two or more orbitals of equal energy...put one electron in each until all are half filled....put one electron in each until all are half filled. carbon

15 RJC For example... Hydrogen hydrogen

16 RJC For example... Oxygen oxygen