CH 301 chapter 3a molecular shape Atkins and Jones

5o therefore the molecule is no longer symmetrical if

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Unformatted text preview: prised of more than one atom around a central atom, we must determine the difference in electronegativity between the central atom and each atom bonded to the central atom. If we determine the difference in electronegativity for each bonded atom around the central atom cancel each other (equal and opposite), the molecule is nonpolar. That is, are all the bonds equally distributed around the central atom? Are the bond angles exactly the same? 52 Electronic vs. Molecular Geometry Molecule Lewis Structure RHED Electronic As predicted by RHED linear Bond Angle Electronic 120o Bond Angle Molecular 120o BeCl2 .. .. : Cl -Be- Cl: Be- Cl: 2 Since the bond angles are the same, the molecular structure is linear. 53 Polarity 1. The representation of a molecule shows a central atom (A) covalently bonded to two atoms (B). 2. The molecule has a linear electronic and molecular structure. 3. Since the bonds are 1800 around the central atom, the dipoles (difference in electronegativity) cancel. 4. The molecule has polar bonds but is nonpolar overall. 54 Polarity of Molecule 55 p.310 Polarity 1. CO2 is an example of a molecule with linear electronic and molecular geometries. 2. The bond angle for both C--O bonds are 180o. 3. The dipoles cancel and the molecule is nonpolar overall. Slide 8 p.308 56 Electronic vs. Molecular Geometry Molecule Lewis Structure RHED Electronic As predicted by RHED Trigonal planar Bond Angle Electronic 120o Bond Angle Molecular 120o BF3 :F: B :F: 3 :F: The bond angles are the same and the molecular structure is trigonal planar. 57 58 p.313 Electronic vs. Molecular Geometry Molecule Lewis Structure RHED Electronic As predicted by RHED Bond Angle Electronic Bond Angle Molecular CH4 H H C H H 4 tetrahedran 109.5o 109.5o The bond angles are the same and the molecular structure is tetrahedran. 59 Polarity All bonded atoms are the same. The difference in electronegativity is the same between the central atom and all bonded atoms. The mo...
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