Friday, September 7, Teaching the Distributive Property After having to reteach my Algebra 2 students the distributive property, I wanted to make sure my Algebra 1 students had a strong understanding of the distributive property. Looking online for ideas, I found the idea of teaching the distributive property using combo meals. I cut them out and laminated them. Then, I glued magnets to the back.
History[ edit ] The composition of coordination complexes have been known since the early s, such as Prussian blue and copper vitriol. The key breakthrough occurred when Alfred Werner reconciled formulas and isomers.
He showed, among other things, that the formulas of many cobalt III and chromium III compounds can be understood if the metal has six ligands in an octahedral geometry. The first to use the term "ligand" were Alfred Stock and Carl Somiesky, in relation to silicon chemistry. The theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the previously inexplicable isomers.
He resolved the first coordination complex called hexol into optical isomers, overthrowing the theory that chirality was necessarily associated with carbon compounds. Crystal field theory In general, ligands are viewed as electron donors and the metals as electron acceptors.
This is because the ligand and central metal are bonded to one another, and the ligand is providing both electrons to the bond lone pair of electrons instead of the metal and ligand each providing one electron.
Bonding is often described using the formalisms of molecular orbital theory. Metal ions preferentially bind certain ligands. In general, 'hard' metal ions prefer weak field ligands, whereas 'soft' metal ions prefer strong field ligands.
Metal ions bound to strong-field ligands follow the Aufbau principlewhereas complexes bound to weak-field ligands follow Hund's rule. Binding of the metal with the ligands results in a set of molecular orbitals, where the metal can be identified with a new HOMO and LUMO the orbitals defining the properties and reactivity of the resulting complex and a certain ordering of the 5 d-orbitals which may be filled, or partially filled with electrons.
In an octahedral environment, the 5 otherwise degenerate d-orbitals split in sets of 2 and 3 orbitals for a more in depth explanation, see crystal field theory. This ordering of ligands is almost invariable for all metal ions and is called spectrochemical series.
For complexes with a tetrahedral surrounding, the d-orbitals again split into two sets, but this time in reverse order.
When the coordination number is neither octahedral nor tetrahedral, the splitting becomes correspondingly more complex. The arrangement of the d-orbitals on the central atom as determined by the 'strength' of the ligandhas a strong effect on virtually all the properties of the resulting complexes.
The absorption of light what we perceive as the color by these electrons that is, excitation of electrons from one orbital to another orbital under influence of light can be correlated to the ground state of the metal complex, which reflects the bonding properties of the ligands.
The relative change in relative energy of the d-orbitals as a function of the field-strength of the ligands is described in Tanabe—Sugano diagrams.
In cases where the ligand has low energy LUMO, such orbitals also participate in the bonding. The metal—ligand bond can be further stabilised by a formal donation of electron density back to the ligand in a process known as back-bonding.
In this case a filled, central-atom-based orbital donates density into the LUMO of the coordinated ligand. Carbon monoxide is the preeminent example a ligand that engages metals via back-donation.
Complementarily, ligands with low-energy filled orbitals of pi-symmetry can serve as pi-donor. Metal— EDTA complex, wherein the aminocarboxylate is a hexadentate chelating ligand. Cobalt III complex containing six ammonia ligands, which are monodentate. The chloride is not a ligand.
Classification of ligands as L and X[ edit ] Main article: Covalent bond classification method Especially in the area of organometallic chemistryligands are classified as L and X or combinations of the two.Revision notes on writing equations in chemistry, how to balance chemical equations, how to read and write formulae, word equations, balancing symbol equations, how to write and balance ionic equations, how to work out a formula from valencies, how to work out formula from the charges on the ions, help when revising for AQA GCSE chemistry A level chemistry, Edexcel GCSE chemistry A level.
Chemical Compounds Practice Quiz This online quiz is intended to give you extra practice in naming compounds, writing formulas and calculating molar masses (formula weights). Select your preferences below and click 'Start' to give it a try! Honors Chemistry is designed for students who have demonstrated strong ability in previous science courses.
In this fast-paced, demanding course, the main topics--which include atomic theory, nuclear chemistry, periodicity, chemical reactions, stoichiometry, gases, solutions, reaction kinetics, equilibrium, acid-base theory, oxidation-reduction, and organic chemistry--are studied at an.
Learn how to name monatomic ions and ionic compounds containing monatomic ions, predict charges for monatomic ions, and understand formulas. Most compounds containing the element carbon are classed as organic compounds.
Formulas for organic compounds are written according to a different set of rules. Practice finding the formula when given the name of an ionic compound.