Molecular Modeling

MOLECULAR MODELING 1. Objectives ? Predictthe incarnation of identified compounds ? Construct molecular(a) models of identified compounds and ? Determine the molecular structure of identified compounds. 2. Theory structure models of molecules atomic number 18 useful for visualizing how atoms are connected in three-dimensional pose called molecular geometry, which is best predicted by Valence-Shell Electron-Pair incompatibility (VSPER) supposition. The following are the sets of rules summarizing thsi theory ? Consider molecules and ions where two or more atoms are bonded to a primaeval atom. The negatron pairs in the valence shell of the central atom are assumed to position as far apart as mathematical because electron pair repels one another. The shape of the molecule or ion is a result of the electron-pair repulsion. ? All the valence-shell electron pairs of the central atom are considered both(prenominal)(prenominal) the pairs that rule covalent bonds (called bonding pa irs) and the pairs that are un shared out (called nonbonding pairs or unaccompanied pairs). ? The nonbonding pairs help to image the position of the atoms in the molecule or ion.Valence Shell-Electron-Pair Repulsion (VSEPR) theory allows the chemist to predict 3-dimensional shape of molecules from knowledge of their Lewis Dot Structure. In VESPR theory, the position of bound atoms (ligands0 and electron pairs are described relative to a central atom. Once the ligands and lone pair electrons are positioned, the resulting geometrical shape presented by the atoms only (ignoring lone pairs) is used to describe the molecule. Electron slow-wittedness and Molecular Geometry d(Be-Cl) = 0,117 nm? = 180 analog (B-F) = 0,130 nm ? = long hundred angulate Planar d(S-O) = 0,150 nm ? = 109 . 5 Tetrahedral d(P-Cleq) = 0,202 nmd(P-Clax) = 0,214 nm? (ClPCl) = 90 ? (ClPCl) = 120 angulate Biplanar d(Xe-F) = 0,190 nm? = 90 Octahedral 3. Apparatus and Materials 2- Modeling Clay (diff. f alsifys) 1 equip (3mm. diameter, 5ft. long) 1- Protractor 4. Procedure 4. 1. Determine the molecular structure of the compounds listed in the table. 4. 2 content the table provided for the experiment. 4. 3 Construct the molecular models for to each one compound. 4. 3. Use color for the central atom diff. from the addicted atoms. Use one color for the attached atoms. 4. 3. 2 Make a 2-inch diameter central atom X and ? inch diameter for the attached atoms Y. 4. 3. 3 Cut the wire into 3 inches long. 4. 3. 4 Attach the central atom X to the Y atoms base on the arrangement. 5. MolecularFormula BondAngles MolecularStructure No. ofBond Pairs No. ofLone Pairs AngularGeometry BeCl2 180 2 0 Linear BF3 120 3 0 TrigonalPlanar SO4 109. 5 4 0 Tetrahedral PCl5 120 5 0 TriangularBipyramidalXeF6 90 6 0 Octahedral 6. Questions 1. What is valence electron? Give its importance. In chemistry,valence electronsare theelectronsof anatomthat can get into in the formation ofchemica bondswith othe r atoms. Valence electrons are their own electrons, present in the free neutral atom, that combine with valence electrons of other atoms to form chemical bonds. In a singlecovalent bondboth atoms contribute one valence electron to form ashared pair. Formain group elements, only the satellitemost electrons are valence electrons.In mutation metals, some inner-shell electrons are also valence electrons. Valence electrons can determine the elements chemical properties and if it will bond with others or not. When two atoms approach each other and react with each other, it is their outer shells that come into contact first, and it is thereof the electrons in their outer shells that are normally involved in whatsoever chemical reaction. So it is the number of electrons in an atoms outer shell that determines, to a large extent, how that element will react chemically.