Bonding common mistakes

Common mistakes

• Confusing ionic with covalent bonding

  Assuming ionic bonds involve sharing of electrons rather than transfer.

  Fix itIonic bonds involve electron transfer and the resulting electrostatic attraction between ions.

• Confusing ionic bonds with covalent bonds

  Students may describe ionic bonds as involving the sharing of electrons.

  Fix itRemember that ionic bonds involve the transfer of electrons, resulting in the formation of charged ions.

• Confusing lattice energy with hydration energy

  Students often treat lattice energy as the same as the energy released when ions dissolve in water, leading to incorrect comparisons.

  Fix itClarify that lattice energy is a property of the solid lattice, whereas hydration energy is the energy released when ions are solvated in a solvent.

• Confusing lattice energy with ionisation energy

  Assuming that the energy required to remove an electron from an atom (ionisation energy) is the same as the energy released when ions form a lattice.

  Fix itClarify that lattice energy is the energy released upon lattice formation, whereas ionisation energy is the energy required to remove an electron from a neutral atom.

• Confusing covalent bonds with ionic bonds

  Assuming that covalent bonds involve electron transfer rather than sharing.

  Fix itClarify that covalent bonds involve shared electron pairs, whereas ionic bonds involve electron transfer leading to charged ions.

• Confusing bond angles with ideal angles

  Students often state the ideal angles for a geometry but fail to recognise that lone pairs compress bond angles between bonding pairs.

  Fix itRemind that lone pairs occupy more space than bonding pairs, reducing the angles between bonds adjacent to a lone pair.

• Ignoring lone pair effects

  Assuming that all tetrahedral molecules have a 109.5° bond angle regardless of lone pairs.

  Fix itAlways identify the number of lone pairs and apply the VSEPR repulsion parameters to adjust the ideal angle.

• Misidentifying molecular shapes

  Confusing the shapes of molecules like NH3 and H2O.

  Fix itRemember that NH3 has a trigonal pyramidal shape due to one lone pair, while H2O has a bent shape due to two lone pairs.

• Confusing delocalised electrons with localized electrons

  Stating that metallic bonding involves localized electrons.

  Fix itRemember that metallic bonding involves delocalised electrons that are free to move throughout the metal lattice.

• Confusing metallic bonding with ionic bonding

  Students may confuse the free movement of electrons in metallic bonding with the fixed positions of ions in ionic bonding.

  Fix itRemember that in metallic bonding, electrons are delocalized and can move freely, while in ionic bonding, electrons are transferred and ions are held in fixed positions.