3.1.3 Bonding

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Cards (12)

Explain why pentan-2-ol has a higher boiling point than pent-1-ene.
Pentan-2-ol contains an O-H bond which is polar and so it forms hydrogen bonding between the molecules whereas in pent-1-ene it only has Van Der Waals forces between molecules. Hydrogen bonding is a stronger intermolecular force than VDW
Explain why a fluoride ion is larger than a sodium ion.
Fluoride ion has a lower nuclear charge than a sodium ion. So there is a weaker force of attraction between the nucleus and the outer electron so it is bigger than a sodium ion.
Explain, in terms of structure and bonding, why the melting point of sodium fluoride is high.
There is a strong electrostatic force of attraction between the Na+ ion and the F- ion so therefore requires lots of energy to overcome the strong bonds
Difference in electronegativity leads to bond polarity
Electronegativity is the power of an atom to withdraw electron density within a covalent bond
Explain how the lone pairs of electrons on the oxygen atom influence the
bond angle in oxygen difluoride.
Lone pairs repel more than bond pairs so the bond angle will be lower than the regular angle
Explain how permanent dipole-dipole forces arise between hydrogen
chloride molecules.
Difference in electronegativity leads to bond polarity and the dipoles don’t cancel therefore the molecule has an overall permanent dipole and there is an attraction between ∂+ on one molecule and ∂− on
another
Shapes of molecules
Linear - 2BP - 180 °
Shapes of molecules sum to 3
Trigonal planar - 3BP - 120 °
Bent - 2BP 1LP - 117.5 °
Shapes of molecules sums to 4
Tetrahedral - 4BP - 109.5 °
Trigonal pyramidal - 3BP 1LP - 107 °
Bent - 2BP 2LP - 104.5 °
Shapes of molecules sums to 5
Trigonal bipyramidal - 5BP - 90 ° 120 °
Seesaw - 4BP 1LP - 117.5 ° 87.5 °
T-shape - 3BP 2LP - 87.5 °
Linear - 2BP 3LP - 180 °
Shapes of molecules sums to 6
Octahedral - 6BP - 90 °
Square pyramidal - 5BP 1LP - 87.5 °
Square planar - 4BP 2LP - 90 °