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CH 103: THE MAGNETIC SUSCEPTIBILITY OF TRISETHYLENEDIAMINE NICKEL (II) CHLORIDE, [Ni(en)3]Cl2 PARAMAGNETIC COMPOUNDS • Paramagnetic compounds have unpaired electrons and are attracted to an external magnetic field. • Liquid oxygen is paramagnetic. It is attracted to an external magnetic field. DIAMAGNETIC COMPOUNDS • In contrast, diamagnetic compounds have no unpaired electrons and are repelled by both poles of an external magnetic field. That is, diamagnetic compounds form an induced magnet field in the opposite direction of an external magnetic field. • Graphite is diamagnetic. It is repelled by an external magnetic field. • The first objective of today’s experiment is to determine if [Ni(en)3]Cl2 is paramagnetic or diamagnetic. d ORBITAL ENERGY LEVEL DIAGRAMS • What is the electron configuration of scandium metal, Sc? • Sc(Z=21): 1s2 2s2 2p6 3s2 3p6 4s2 3d1 • What is the electron configuration of scandium ion, Sc2+? • Hint: The outmost s electrons of a transition metal are generally removed before the outmost d electrons. • Sc2+(Z=21): 1s2 2s2 2p6 3s2 3p6 3d1 • The d orbital energy level diagram for Sc2+ follows. Is Sc2+ paramagnetic or diamagnetic? or more accurately • Paramagnetic, Sc2+ has 1 unpaired electron. THE GRAM MAGNETIC SUSCEPTIBILITY, χg THE MOLAR MAGNETIC SUSCEPTIBILITY, χM • Use the periodic table in the front of your laboratory manual to calculate the molecular weight o of the sample, [Ni(en)3]Cl2 or [Ni(NH2CH2CH2NH2)3]Cl2. THE CORRECTED MOLAR MAGNETIC SUSCEPTIBILITY, χA • The ethylenediamine ligands (NH2CH2CH2NH2) and the chloride ions (Cl-) are diamagnetic and are repelled by the external magnetic field. • Therefore, the deflection (D) is artificially small, and the Molar Magnetic Susceptibility (χM) is artificially small. • This is corrected by the following equation. THE CORRECTED MOLAR MAGNETIC SUSCEPTIBILITY, χA THE MAGNETIC MOMENT AND THE NUMBER OF UNPAIRED ELECTRONS • Calculate the magnetic moment from the following equation. • Calculate the number of unpaired electrons (n) from the following equation. SAFETY • Give at least 1 safety concern about using [Ni(NH2CH2CH2NH2)3]Cl2 in today’s experiment. • This is an irritant. Wear your goggles at all times. Immediately clean all spills. If you do get either of these in your eye, immediately flush with water. • Your laboratory manual has an extensive list of safety procedures. Read and understand this section. • Ask your instructor if you ever have any questions about safety. SOURCES • “Diamagnetic graphite levitation” by en:User:Splarka English Wikipedia. Licensed under Public domain via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Diamagnetic_graphi te_levitation.jpg#mediaviewer/File:Diamagnetic_graphite_le vitation.jpg [accessed 28 August 2014]. • McMurry, J., R.C. Fay. 2004. Chemistry, 4th ed. Upper Saddle River, NJ: Prentice Hall. • “Paramagnetism of liquid oxygen” by Pieter Kuiper - Own work. Licensed under Public domain via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Paramagnetism_of_ liquid_oxygen.jpeg#mediaviewer/File:Paramagnetism_of_liq uid_oxygen.jpeg [accessed 28 August 2014]. • Petrucci, R.H. 1985. General Chemistry Principles and Modern Applications, 4th ed. New York, NY: Macmillan Publishing Company.