The shape of the lesson
By the end of the lesson, learners can
- Physical properties: Push the layers of ions in the simulator and watch them slide while the sea of electrons holds them together.
- Chemical properties: Metals share three general reactions.
- Physical: conductors, malleable, ductile, high melting point.
- Acid: salt + hydrogen.
- Cold water: hydroxide + hydrogen. Steam: oxide + hydrogen.
- Oxygen: metal oxide.
One picture every idea returns to
Metals are good conductors of heat and electricity, malleable (can be hammered into shape) and ductile (can be drawn into wires), and usually have high melting and boiling points. Non-metals are generally poor conductors and brittle when solid. Metals react with dilute acids to give a salt and hydrogen, with cold water or steam to give a hydroxide or oxide and hydrogen, and with oxygen to give metal oxides.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Shiny, strong and conducting.. Metals conduct, bend without breaking and melt only at high temperatures, while most non-metals do the opposite. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Physical properties | Push the layers of ions in the simulator and watch them slide while the sea of electrons holds them together. Project tab 4 of the lab (Chemical bonding lab, metallic bonding) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Chemical properties | Metals share three general reactions. | Rally Robin |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 15 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Chemical properties, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Rally Robin
Pairs take turns to say one item each, back and forth: a definition, a unit, a step of the method. Keep it fast and oral; the point is retrieval, not writing.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| With cold water a reactive metal forms a hydroxide; with steam a metal forms an oxide. | Magnesium reacts only very slowly with cold water but burns in steam to give magnesium oxide. |
Properties of metals: worksheet
6 questions, 15 marks. Written in the style of the papers; no past paper question is reproduced.
Give four physical properties that are typical of metals.
Write a word equation and a balanced symbol equation for the reaction of magnesium with dilute hydrochloric acid.
A student has samples of two solid elements. P is shiny, bends when hammered and conducts electricity. Q is yellow, shatters when hit and does not conduct. Identify each as a metal or non-metal and suggest what each could be.
State the products when (a) sodium reacts with cold water and (b) zinc reacts with steam.
Write the balanced equation for magnesium burning in oxygen and describe what is seen.
Explain why metals are malleable, in terms of their structure.
Answer key and marking notes
- Good conductors of electricity.
- Good conductors of heat.
- Malleable and ductile.
- High melting and boiling points (and shiny when freshly cut).
- magnesium + hydrochloric acid → magnesium chloride + hydrogen
- Mg + 2HCl → MgCl2 + H2
- P is a metal (for example copper or iron).
- Q is a non-metal (for example sulfur).
- Reason: conductivity and malleability are metallic; brittleness and poor conductivity are non-metallic.
- (a) sodium hydroxide and hydrogen.
- (b) zinc oxide and hydrogen.
- 2Mg + O2 → 2MgO
- A bright white flame; a white powder (magnesium oxide) is left.
- Metals consist of layers of positive ions in a sea of delocalised electrons.
- The layers can slide over each other without the metallic bonding breaking.
7 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Solid copper conducts electricity well. What is the reason for this?
- Aits structure contains delocalised electrons that are free to move
- Bits positive ions are free to move through the solid towards the electrodes
- Cits atoms share pairs of electrons in covalent bonds
- Dit contains negative ions that carry the charge
The table gives data for four solid elements.
| Element | Melting point / °C | Conducts when solid? | When hammered |
|---|---|---|---|
| W | 1538 | yes | flattens |
| X | 115 | no | shatters |
| Y | 3652 | yes | shatters |
| Z | 44 | no | crumbles |
- AW
- BX
- CY
- DZ
Iron filings are added to dilute hydrochloric acid. Which products form?
- Airon(II) chloride and hydrogen
- Biron(II) chloride and water
- Ciron oxide and hydrogen
- Diron(II) chloride and chlorine
Aluminium powder burns in oxygen to form aluminium oxide, Al2O3. Which is the balanced equation?
- A4Al + 3O2 → 2Al2O3
- B2Al + O2 → 2AlO
- C2Al + 3O2 → Al2O3
- DAl + O2 → AlO2
A small piece of potassium is added to a trough of water containing universal indicator. The potassium fizzes and the indicator turns purple. What does the colour change show?
- Aan alkali, potassium hydroxide, has been formed
- Bthe hydrogen produced has made the water acidic
- Cpotassium oxide, an acidic oxide, has formed
- Dthe water has been heated, which always turns indicator purple
A grey solid element conducts electricity and has a very high melting point, but it is brittle and cannot be drawn into wires. What is the best description of this element?
- Aa non-metal, such as carbon in the form of graphite
- Ba metal, because it conducts electricity
- Ca metal, because it has a very high melting point
- Dan alloy of two metals
Magnesium ribbon fizzes in dilute hydrochloric acid. Which is the ionic equation for the reaction?
- AMg(s) + 2H+(aq) → Mg2+(aq) + H2(g)
- BMg(s) + 2Cl−(aq) → MgCl2(aq)
- CMg2+(aq) + H2(g) → Mg(s) + 2H+(aq)
- DMg(s) + H+(aq) → Mg+(aq) + H(g)
Quiz key
A metal is a lattice of positive ions in a sea of delocalised electrons. When a voltage is applied, these electrons drift through the structure and carry the current. The positive ions in a solid metal stay in fixed positions, so they cannot move to the electrodes. Covalent bonding describes non-metals, and a pure metal contains no negative ions.
W has a high melting point, conducts electricity and flattens instead of breaking, so it is malleable: every property fits a metal (the data match iron). Y conducts and has a very high melting point, but it is brittle, which fits graphite, a form of the non-metal carbon. X and Z have low melting points, do not conduct and are brittle, which is typical of non-metals such as sulfur and phosphorus.
A metal above hydrogen reacts with a dilute acid to give a salt and hydrogen: Fe + 2HCl → FeCl2 + H2. The salt of hydrochloric acid is a chloride, here iron(II) chloride. Water is formed when an acid reacts with a base or carbonate, not with a metal. An oxide would need oxygen, and chlorine is not released because the chlorine stays in the salt as chloride ions.
Two units of Al2O3 contain 4 Al and 6 O atoms, which are supplied by 4Al and 3O2, so 4Al + 3O2 → 2Al2O3 is balanced. The equations giving AlO or AlO2 use wrong formulae for the oxide, which contains Al3+ and O2− ions. The equation with 3O2 but only one Al2O3 has 6 oxygen atoms on the left but only 3 on the right.
Reactive metals react with cold water to give a metal hydroxide and hydrogen: 2K + 2H2O → 2KOH + H2. Potassium hydroxide is a strong alkali, so the indicator turns purple (high pH). Hydrogen is only slightly soluble and does not make water acidic. Metal oxides are basic, not acidic, and cold water forms the hydroxide rather than the oxide. Warming water does not turn the indicator purple.
Metals are malleable and ductile, so a brittle solid that cannot be drawn into wires is not behaving like a metal. Graphite, a form of carbon, is the classic non-metal that conducts electricity and has a very high melting point. Conductivity and a high melting point alone do not prove an element is a metal. An alloy is a mixture, not an element, and alloys are still malleable.
Magnesium atoms lose two electrons to form Mg2+ ions, and two hydrogen ions gain those electrons to form a hydrogen molecule, so Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g). Chloride ions are spectators and are left out. The reversed equation would turn magnesium ions back into the metal, which does not happen because magnesium forms positive ions readily. Magnesium forms 2+ ions and hydrogen gas is diatomic, so Mg+ and H are wrong.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.