ch8 - Chapter 8 Electron Configurations and Chemical...

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Chapter 8 Electron Configurations and Chemical Periodicity Chapter goals Understand the role magnetism plays in determining and revealing atomic structure. Understand effective nuclear charge and its role in determining atomic properties. Write the electron configuration of neutral atoms and monatomic ions. Understand the fundamental physical properties of the elements and their periodic trends. Electron spin: the Fourth Quantum Number The fourth quantum number is the spin quantum number, m s . It has two possible values. m s = +½ , or −½ , or m s = ± ½ This quantum number tells us the spin and orientation of the magnetic field of the electrons. Wolfgang Pauli discovered the Exclusion Principle in 1925. No two electrons in an atom can have the same set of 4 quantum numbers, n, l , m l , and m s Paramagnetism and Diamagnetism Unpaired electrons have their spins aligned or (in diff. orbitals) This increases the magnetic field of the atom. Total spin 0, because they add up. Atoms with unpaired electrons are paramagnetic . Paramagnetic atoms are attracted to a magnet. Paramagnetism and Diamagnetism The spins are not aligned in paired electrons  . Paired electrons have no net magnetic field. Total spin = 0, (+½ , -½) Atoms with no unpaired electrons are called diamagnetic . Diamagnetic atoms are not attracted to a magnet. Atomic Subshell Energies and Electron Assignments The process for obtaining the electronic structure of an atom is the Aufbau Principle. Start at lowest energy orbital 1s then 2s, then 2p, followed by 3s, etc
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Atomic Subshell Energies and Electron Assignments One mnemonic to remember the correct filling order for electrons in atoms is the increasing n + value n 8 7 6 5 4 3 2 1 0 8s 7s 6s 5s 4s 3s 2s 1s 2 6d 5d 4d 3d 3 5f 4f 1 7p 6p 5p 4p 3p 2p Atomic Electron Configurations Electronic configurations of the elements on the periodic table (Aufbau Principle). 1 st row elements: H, He [He] or 1s He 1s H ion Configurat 1s 2 2 1 1  Atomic Electron Configurations Hund’s rule tells us that the electrons will fill the p orbitals by placing electrons in each orbital singly and with same spin until half-filled. Then the electrons will pair to finish the p orbitals. 2nd row: Li-Ne Atomic Electron Configurations 3 rd row elements: Na-Ar 6 2 18 5 2 17 4 2 16 3 2 15 2 2 14 1 2 13 2 12 1 11 3p s 3 Ne Ne Ar 3p s 3 Ne Ne Cl 3p s 3 Ne Ne S 3p s 3 Ne Ne P 3p s 3 Ne Ne Si 3p s 3 Ne Ne Al s 3 Ne Ne Mg s 3 Ne Ne Na ion Configurat 3p 3s              Atomic Electron Configurations
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This note was uploaded on 09/08/2010 for the course CHM 2045 taught by Professor Vxv during the Spring '10 term at College of the Canyons.

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ch8 - Chapter 8 Electron Configurations and Chemical...

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