1
Confusing intermolecular forces with covalent bonds in questions about simple molecular substances
“candidates need to take care on the use of terminology. Although it is less common to read candidate answers that refer to the breaking of covalent bonds, not all answers correctly describe intermolecular forces.”— 4CH1 Paper 1C, June 2023
How to fix: Simple molecular substances (e.g. iodine, water, hydrocarbons) have strong covalent bonds WITHIN molecules and weak intermolecular forces BETWEEN molecules. Low melting points are due to weak intermolecular forces being overcome, NOT due to breaking covalent bonds. Always state: (1) the forces between molecules are WEAK intermolecular forces; (2) only a SMALL amount of energy is needed to overcome them. 'Less energy' alone is ambiguous — say 'a small amount of energy'.