Metals

Traps in Metals

• Reverses a trend, direction or effect
  State the rule with its direction before looking at the options (down group 1 reactivity INCREASES; exothermic forward reaction: heating shifts LEFT). An option that is the mirror image of the rule is the trap.
• Confuses metal extraction methods
  Very reactive metals (K, Na, Ca, Mg, Al) are extracted by electrolysis; moderately reactive (Zn, Fe, Pb) by carbon reduction; unreactive (Au) occur native.
• Picks a related substance or process with a different role
  Learn reagents and processes as one-line 'name → job' cards and contrast neighbours in a table (process | product | catalyst | conditions). Match the job in the stem, not just the topic.
• Oxidation/reduction definition errors
  OIL RIG: Oxidation Is Loss of electrons, Reduction Is Gain. The oxidising agent is itself reduced. Oxidation number increases on oxidation.
• Uses everyday or macroscopic thinking instead of particles
  Ask what the particles, ions or electrons are doing. Properties of a substance come from its particles and bonds, not from how it looks or feels.
• Takes one factor as the whole answer
  Ask whether the option is necessary or sufficient. If the stem involves two changes or two conditions, both must appear in the answer.
• Properties of metals and compounds errors
  Reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au. Amphoteric oxides/hydroxides: Al, Zn, Pb. Rusting needs BOTH water and oxygen; prevented by painting, galvanising (zinc), sacrificial protection.
• Mixes up a pair of similar chemical terms
  Keep a list of confusable pairs with one defining feature each and a hook. Underline the key word in the stem and check it against the definition, not the sound of the name.
• Puts a substance or reaction in the wrong class
  Classify from the defining feature: functional group for organic series; bond type and structure for properties; reaction with acid AND alkali for amphoteric. Check each option against the feature, not the name.
• Chooses a true but irrelevant statement
  Re-read the question word (why, which, what causes). A true fact that answers a different question is still wrong.
• Over-generalises a rule beyond where it holds
  Every rule in chemistry has conditions. Before applying one, check the conditions in the stem (electrode type, concentration, moles of gas on each side, metal position).
• Confuses types of chemical bonding
  Ionic: electron TRANSFER metal → non-metal (NaCl). Covalent: electron SHARING between non-metals (H₂O). Dative: both shared electrons from one atom (NH₄⁺). Metallic: cations in a sea of electrons.