Chemical Reactions and the Periodic Table
MYP Sciences Year 3 — Chemical Reactions and the Periodic Table
This unit is really two things stitched together: a map of the elements (the periodic table) and the rules for how substances change into new ones (chemical reactions). Every exam question you'll see is one of three moves — read a property off the table, predict how reactive something is, or spot the evidence that a reaction actually happened. Get comfortable naming specific evidence and specific metals, because vague answers ('it changed', 'it's a metal thing') are exactly where marks get dropped.
Overview — How This Topic Fits Together
The periodic table isn't just a poster on the wall — it's a prediction machine. Once you know where an element sits, you can predict its physical properties (metal or non-metal?), how it will react (reactivity series), and what kind of reaction it's likely to undergo. The skill examiners actually test is linking these three ideas: position → properties → reactivity → observable evidence.
- Metals and non-metals differ in structure (electron behaviour) — that structure explains every physical property question you'll get.
- The periodic table organises elements by proton number into periods (rows) and groups (columns) — position predicts behaviour.
- The reactivity series ranks metals by how easily they lose electrons — this decides what reacts with what, and how metals are extracted.
- Reactions fall into a handful of recognisable types (synthesis, decomposition, displacement, combustion) — spotting the type from an equation is a core skill.
- A chemical change always leaves evidence — gas, colour, precipitate, temperature, light/odour — but that evidence must be linked to a new substance, not just assumed.
The shape of the chapter
Command terms this topic loves to test
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| State / Identify | Give a short, precise answer — a name, term or single fact, no reasoning required. | MYP Criterion A | Award 1 mark for the correct word/name only — extra explanation earns nothing but wastes time. |
| Describe | Give a detailed account with relevant facts, but no explanation of why. | MYP Criterion A/B | Marks go for accurate observations or trends (e.g. 'bubbles decrease from Mg to Cu'), not for cause. |
| Explain | Give reasons or a mechanism — the 'why' or 'how', usually linking cause to effect. | MYP Criterion A | No mark without the causal link — 'rust forms because iron is exposed' is incomplete without stating oxygen/water reacting with iron. |
| Analyse | Break an issue into parts and show relationships between them — often cost vs benefit, or trend vs cause. | MYP Criterion D | One-sided answers (only costs, only benefits) cap at half marks — both sides must be weighed. |
| Evaluate | Weigh strengths and weaknesses to reach a justified judgement. | MYP Criterion D | A judgement with no reasoning ('stainless steel is better') scores zero — the weighing is the mark. |
Key point
Overview