IB Chemistry Metallic Bonding: FAQs, Exam Technique & Common Mistakes

Metallic bonding is the electrostatic attraction between a lattice of positive metal cations and a "sea" of delocalised electrons. It sits in Structure 2.3 of the current IB Chemistry guide (first exams 2025). This shared electron sea, rather than fixed bonds between pairs of atoms, is why metals conduct electricity and can be bent without shattering.

Metals conduct because the delocalised electrons in the electron sea move freely through the whole lattice rather than being tied to one atom. Apply a voltage and these electrons drift toward the positive terminal, carrying charge — mobility that a fixed ionic lattice or a covalent network simply doesn't have.

Three things: the cation's charge, its ionic radius, and the number of delocalised electrons per atom. Higher charge, smaller radius and more delocalised electrons all pull the electron sea in tighter, raising the melting point — exactly why aluminium melts far higher than sodium.

Neither is universally stronger — it depends on the specific ions or atoms involved. Ionic bonds between small, highly-charged ions (like in magnesium oxide) are often stronger than metallic bonds in soft metals like sodium, while metallic bonding in tungsten can beat many ionic lattices. Compare like-for-like, never the whole category.

Describe the structure first — a lattice of cations in a sea of delocalised electrons — then link it directly to whatever property the question asks about, whether that's conductivity, malleability or melting point. Examiners mark the causal chain, not just the model's name, so never stop at "electrostatic attraction" without saying attraction between what and what.

"State" wants the electron-sea structure in one sentence. "Explain" wants that structure linked to a cause — usually bond strength or electron mobility. "Deduce" or "predict", more common at HL, asks you to apply the charge/radius/electron trend, like ranking melting points across Period 3 metals from data given.

The most common slip is writing "electrons are shared" or "electrons are transferred" — language borrowed from covalent and ionic bonding. In the metallic model, electrons are delocalised across the entire lattice, belonging to no single atom or ion pair, and examiners specifically flag sharing/transferring wording as a genuine model confusion, not just sloppy phrasing.

Metallic bonding is a lattice of cations from the same element surrounded by delocalised electrons from those same atoms. Ionic bonding is a lattice of alternating cations and anions from different elements, held by electrostatic attraction between fixed, oppositely-charged ions. That's the structural reason metals conduct as solids and ionic compounds don't.

There are no fixed bonds between specific atoms to break, so layers of cations can slide past each other under stress without shattering the lattice. The delocalised electrons simply flow around the new positions and keep holding everything together — contrast that with an ionic lattice, where sliding brings like charges together and the whole thing fractures.

Yes — the core electron-sea model in Structure 2.3 is identical content for SL and HL. HL students are pushed further, using the model to predict trends in melting point across a period and to compare bond strength quantitatively using charge, radius and electron count together, often in longer extended-response questions.

Yes — alloys sit within Structure 2.3 as mixtures of metals (or a metal with another element) where atoms of different sizes distort the regular lattice. That distortion is exactly why alloys like steel are harder than pure iron: irregular atom sizes stop layers sliding past each other as smoothly as they do in the pure metal.

Not conceptually hard — but it's one of the topics students most reliably lose easy marks on, usually through mixing metallic language with ionic or covalent phrasing. Once you've drilled the electron-sea explanation for conductivity, malleability and melting-point trends, it becomes one of the more reliably scorable parts of Structure 2.

Practise past-paper questions that ask you to explain a property from the structure, not just describe the structure on its own. Build a short table linking each property — conductivity, malleability, melting point — to the specific structural feature causing it, then test yourself without notes until the wording comes out without hesitation.

You don't need a chemistry background to help. Ask your child to explain, out loud and without notes, why metals conduct electricity or bend without breaking. If they can't do it in plain English, they haven't fully learned it yet — that's the quickest home check before a mock exam.