Bonding questions Flashcards
Compare the bonding between Na and Mg
Mg has a stronger metallic bonding than Na and hence a higher boiling point
Metallic bonding is stronger in Mg than Na as there are more electrons released into the sea of electrons. Mg ion is also smaller and has one more proton. Stronger electrostatic attraction between the positive metal ions and the delocalised electrons high energy is needed to break bonds
Explain why the bp of pentan -2-ol is higher than the bp of pent-1-ene
Pentan-2-ol has stronger inter molecular forces
pent1ene has van deer waals only
pentan1ol has hydrogen bonds too which are stronger than van deer waals
Explain why mp of xef4 is different to the mp of pf3
Stage 1 electron pairs
1a XeF4 4BP and 2LP around Xe
1b PF3 3BP and 1LP around P
Stage 2 explanation of shapes
2a XeF4 is square planar
2b PF3 is pyramidal (allow tetrahedral)
2c Electron pairs repel as far as possible or Lone pair repels more than bonding
pairs
Stage 3 IMF
The relative strength of the intermolecular forces in the molecules must be
explained to gain maximum marks.
3a XeF4 has vdw forces and PF3 has dipole-dipole forces (and vdw)
3b Stronger/more intermolecular forces in XeF4
3c Due to larger Mr or more electrons or larger molecules or packs more closely
together
Explain why a flouride ion is larger than a sodium ion
- Flourine has two fewer protons
- Weaker electrostatic attraction of outer electrons to the nucleus
Name the type of bond formed when a proton is added to hydrogen flouride
- co ordinate bond
- flourine donates a lone pair of electrons to the H
