Chem 1120 1st Edition Lecture 22 Outline of Last Lecture I Other Group 6A Elements II Nitrogen Family III Allotropes Carbon Family Boron Family Outline of Current Lecture I Transition Metal Properties and Trends II Magnetism III Coordination Complexes and Ligands Current Lecture I Most metals including transition metals are found in solid inorganic compounds known as minerals minerals are named by common not chemical names Partially filled d orbitals multiple oxidation states 3 to 8 s orbitals are filled first except Cr Cu Unpaired electrons paramagnetic magnetic properties Colors from electron transitions between d orbitals Coordination compounds with 4 9 ligands Most transition metal ions colorful and paramagnetic except those with d10 configuration These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Atomic Radii trends in atomic radii are similar across all three rows of transition metals while effective nuclear charge increases across a row so does the number of nonbonding electrons therefore these repel each other and increase the radius also metallic bonding strength increases to middle and then decreases as anti bonding orbitals are filled These effects work together to decrease and counteract to lead to increase General trend Bonds shorten as they become stronger Atomic size remains fairly constant as atomic number increases you go across the periodic table because electrons are added to inner shells shielding outer electrons from nuclear charge efficiency II Magnetism can be used to analyze d electron populations Three major types of magnetic behavior Diamagnetic no atoms or ions with magnetic moments Paramagnetic magnetic moments unaligned without a magnetic field Ferromagnetic coupled magnetic centers aligned in common direction without magnetic field Ferrimagnetism Ferrimagnetic substances have spins that align opposite each other but the spins are not equal so there is a net magnetic field This can occur because magnetic centers have different numbers of unpaired electrons and more sites align in one direction than the other Antiferromagnetism Antiferromagnetic substances have unpaired spins on adjacent atoms that align in opposing directions these magnetic fields tend to cancel each other III Commonly transition metals can have molecules or ions that bond to them these give rise to complex ions or coordination compounds The molecules or ions that bind to the central metal are called ligands molecules and or anions with one or more donor atoms that each donate a lone pair of electrons to the metal ion to form a covalent bond Monodentate ligands coordinate to one site on the metal bidentate to two and polydentate to more than two bi and poly dentate ligands are also called chelating agents Coordination complexes compounds formed by Lewis acid base interactions a coordinate covalent bond transition metals or their ions are Lewis acids and ligands are Lewis bases Complexes metal atom or ion bonded to by ligands complexes do not dissociate into ions they act as a single molecule or ion lots of different colored complexes Square brackets enclose the complex ion while counterions are outside the brackets Number of ligands bound to metal coordination number Metal atom the ligands bound to it coordination sphere