Did you know? Aluminium oxide can behave as an acid or a base depending on the reaction partner. Magnesium oxide is basic; silicon dioxide is acidic, yet silicon dioxide does not simply dissolve in water to create a strong acid. This apparent puzzle explains an important Period 3 pattern.
This original JC1 H2 Chemistry tutor guide compares six oxides named in SEAB’s 2027 syllabus 9476. It connects bonding, oxidation number, water reaction, acid-base behaviour, amphoterism and the balanced equations students need to explain the changing chemistry of Period 3.
The equations are paper teaching models. No learner should mix reactive oxides with water, acids or sodium hydroxide outside a school laboratory. The unchanged eduKateSG Clementi teaching reference and the Hougang Chemistry library provide the learning architecture.
EDUKATESG · HOUGANG · JC1 H2 CHEMISTRY
14 chapters · Period 3 matrix · Transfer questions · FAQs · Official syllabus
Full chapter index
- 1. Start with the surprising middle of Period 3
- 2. Interpret oxide names, formulas and oxidation states
- 3. Predict why sodium oxide gives strongly basic products
- 4. Explain MgO as a basic oxide without exaggerating its solubility
- 5. Understand what amphoteric actually demands
- 6. Balance the aluminium oxide plus acid equation
- 7. Balance aluminium oxide with sodium hydroxide in water
- 8. Compare the amphoteric hydroxide Al(OH)₃
- 9. Why silicon dioxide is acidic but not an ordinary soluble acid
- 10. Move right to phosphorus(V) oxide and sulfur(VI) oxide
- 11. Relate the oxide trend to bonding and structure
- 12. Separate acidity of an oxide from pH of a suspension
- 13. Catch equations and exceptions that cause errors
- 14. Transfer to an unfamiliar oxide without memorising the Period 3 list
1. Start with the surprising middle of Period 3
Across the third period, the familiar oxides shift from strongly basic behaviour on the metallic side toward acidic behaviour on the non-metallic side. Sodium oxide Na₂O and magnesium oxide MgO are classified as basic oxides in the standard syllabus treatment. Aluminium oxide Al₂O₃ is amphoteric: it can react with acids and with suitably strong alkalis. Silicon dioxide SiO₂ is an acidic oxide, even though it is not appreciably soluble in ordinary water.
This is not a smooth change in which every oxide dissolves progressively faster or produces a neat colour scale. The bonding and structures also change. Sodium and magnesium oxides have extensive ionic character; aluminium oxide combines substantial ionic character with polarisation and covalent contribution; silicon dioxide is an extended covalent network. Phosphorus(V) oxide and sulfur(VI) oxide provide acidic non-metal oxides further to the right.
One tutor question brings the pattern into focus: What makes aluminium oxide behave differently from magnesium oxide and silicon dioxide, when all contain oxygen? Students should not answer merely that aluminium has proton number thirteen. The chemical behaviour arises from interactions of the oxide with acids and strong bases, along with its bonding and reaction products.
The 2027 H2 Chemistry 9476 syllabus specifically names Na₂O, MgO, Al₂O₃, SiO₂, P₄O₁₀ and SO₃ for reactions with water and acid/base behaviour. A good explanation must therefore account for each member, not replace the exact named list with unsupported general claims about every conceivable Period 3 oxide.
Ask the student: Which named oxide lies between the basic and acidic categories in this comparison?
Evidence of understanding: Al₂O₃, which exhibits amphoteric behaviour.
2. Interpret oxide names, formulas and oxidation states
Na₂O contains sodium in oxidation state +1 and oxygen in −2. MgO contains magnesium in +2. Al₂O₃ has aluminium in +3; SiO₂ has silicon in +4; phosphorus is +5 in P₄O₁₀; sulfur is +6 in SO₃. These oxidation numbers are chemical bookkeeping for the compounds, not direct measurements of isolated ions in all structures.
The highest common oxidation number increases across the named oxides in the standard Period 3 trend. This aligns with the growing number of valence electrons available for bonding across sodium to sulfur, with important differences in structure and the interpretation of formal oxidation states.
Oxidation number alone cannot completely predict whether an oxide is acidic or basic. For example, the nature of bonding, solvation and possible reaction products all matter. It is helpful to recognise the correlation across these named oxides while avoiding a universal rule that any element at oxidation state +4 must produce an acidic oxide.
A useful worksheet has two columns: compound formula and element oxidation state. Before discussing the reaction with water, ask the student to verify charge balance or electron bookkeeping as appropriate to the structure. An incorrect formula can lead to a wrong stoichiometric equation even if the student’s idea about amphoterism is otherwise sound.
Ask the student: What is the formal oxidation state of aluminium in Al₂O₃?
Evidence of understanding: +3, because three O atoms contribute a total of −6 in the conventional formula.
3. Predict why sodium oxide gives strongly basic products
Sodium oxide is treated as a strongly basic oxide of an electropositive metal. In the school model it reacts with water to form sodium hydroxide: Na₂O + H₂O → 2NaOH. This equation is balanced for two Na, two H and two O atoms. The hydroxide formed can provide OH⁻ ions in aqueous solution.
The formation of a basic aqueous product links the chemical reaction to the oxide’s classification. But the equation does not mean every basic oxide simply dissolves without a chemical change. In this case the oxide reacts with water, and the product is a hydroxide; that distinction matters when interpreting a solid disappearing into a liquid.
On the structural side, strong electrostatic attraction exists between ionic constituents of the solid oxide. Its ability to form hydroxide in water and to undergo acid neutralisation should be understood through the specified chemical reactions rather than visual appearance of a white powder.
Do not encourage students to handle sodium oxide independently. It reacts vigorously with water and the products are caustic. All reaction comparisons in this article are conceptual or based on supplied equations rather than instructions for chemical preparation.
Ask the student: What balanced reaction represents Na₂O forming sodium hydroxide?
Evidence of understanding: Na₂O + H₂O → 2NaOH.
4. Explain MgO as a basic oxide without exaggerating its solubility
Magnesium oxide is also a basic oxide. In water, the simplified formula change is MgO + H₂O → Mg(OH)₂. The resulting magnesium hydroxide is sparingly soluble in water, so the observed aqueous behaviour is not identical to that of sodium hydroxide despite both being basic compounds.
This difference exposes a frequent exam mistake: a student sees MgO classified as basic and concludes that adding it to water must form a concentrated, perfectly clear solution of a strong soluble alkali. The chemical formula predicts hydroxide formation, but the amount dissolving depends on solubility and other conditions.
Magnesium oxide reacts with an acid in the conventional neutralisation-type equation MgO + 2HCl → MgCl₂ + H₂O. The oxide accepts acidic protons and produces salt and water in this model. This is direct evidence for its basic oxide behaviour.
An H2 answer should not say MgO is amphoteric simply because a different magnesium compound might have complicated solution chemistry. For the named Period 3 classification and usual school reaction conditions, MgO is basic, while Al₂O₃ demonstrates the important amphoteric contrast.
Ask the student: Why should a student not describe the product of MgO and water as a highly soluble strong alkali without qualification?
Evidence of understanding: Mg(OH)₂ has limited aqueous solubility, so hydroxide formation and dissolution extent are distinct.
5. Understand what amphoteric actually demands
An amphoteric oxide can undergo acid-base reactions with both acids and strong bases under suitable conditions. Aluminium oxide is the central Period 3 example. Calling it amphoteric is not merely saying it has ‘medium pH’ or falls halfway between metal and non-metal atomic numbers.
In an acidic environment, oxide-associated basic sites can be protonated and soluble aluminium-containing products may form. In a suitably alkaline environment, aluminium-containing hydroxide complexes can form as the solid reacts with the base. The reaction partners and products differ, but both count as acid-base behaviour.
Many students memorise the word ‘amphoteric’ without providing two contrasting equations. A stronger learning exercise asks for one balanced reaction of Al₂O₃ with acid and one with aqueous sodium hydroxide under the specified conditions. These equations give evidence that the oxide is neither only basic nor only acidic.
The 2027 syllabus explicitly specifies reactions with sodium hydroxide only and acids in the amphoteric behaviour outcome. A tutor should therefore not require a large catalogue of unrelated bases, exotic complex ions or industrial processing conditions simply to explain the examined principle.
Ask the student: What two kinds of reaction must be shown to support the word amphoteric?
Evidence of understanding: A reaction with an acid and a reaction with a strong base such as aqueous NaOH.
6. Balance the aluminium oxide plus acid equation
One familiar paper equation is Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O. It shows the oxide reacting with hydrochloric acid to form an aluminium salt and water. Check the counts: two aluminium atoms, six chlorine atoms, six hydrogens and three oxygen atoms appear on both sides.
The coefficients matter. A student who writes Al₂O₃ + 3HCl → AlCl₃ + H₂O has not balanced aluminium, hydrogen or oxygen correctly. This is not a minor presentation error when a problem asks for reacting amounts. Stoichiometry follows from the actual balanced chemical equation.
The acid does not simply ‘dissolve a neutral powder’ in the same sense as dispersing sugar in water. It participates in a chemical reaction, and the aluminium-containing species in solution depend on the stated chemical environment. For a basic exam model, AlCl₃ is a convenient formula product with water.
Do not assume a solid oxide is instantly consumed in any acid, regardless of particle size, concentration or conditions. The chemical equation gives a possible net transformation and stoichiometric relationship; an actual reaction rate or completion is a separate matter requiring evidence.
Ask the student: Which coefficient is needed before HCl when balancing Al₂O₃ + HCl → AlCl₃ + H₂O?
Evidence of understanding: Six, giving Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O.
7. Balance aluminium oxide with sodium hydroxide in water
In a suitably alkaline aqueous model, aluminium oxide can react to give tetrahydroxoaluminate species. A commonly used ionic representation is Al₂O₃ + 2OH⁻ + 3H₂O → 2[Al(OH)₄]⁻. With sodium ions supplying the counterions, this may be written Al₂O₃ + 2NaOH + 3H₂O → 2Na[Al(OH)₄].
Check the ionic equation. There are two aluminium atoms on both sides. Oxygen totals three in oxide, two in hydroxide and three in water, giving eight; the two product complexes each contain four oxygen atoms. Hydrogen totals two plus six, giving eight. Net electrical charge is −2 on both sides.
This equation illustrates the chemically important fact that Al₂O₃ can respond to strong base even though MgO behaves as a basic oxide in the standard comparison. The presence of water in the balanced aqueous equation is essential; it should not be discarded when checking the hydroxide complex.
The formula [Al(OH)₄]⁻ is a useful aqueous representation, not proof that all aluminium-containing solutions have only one coordination species under every concentration or temperature. Students should use the form given or accepted for their syllabus and the supplied conditions, avoiding unnecessary claims of universal speciation.
Ask the student: What aluminium-containing anion is represented in the aqueous NaOH model?
Evidence of understanding: [Al(OH)₄]⁻, the tetrahydroxoaluminate ion.
8. Compare the amphoteric hydroxide Al(OH)₃
Aluminium hydroxide is another familiar amphoteric substance. In an acid, Al(OH)₃ + 3H⁺ → Al³⁺ + 3H₂O represents dissolution under the simple acidic model. In excess aqueous hydroxide, Al(OH)₃ + OH⁻ → [Al(OH)₄]⁻ shows formation of a soluble aluminium hydroxo complex.
These paired reactions are convenient because the same solid hydroxide is the starting material in both cases. Students can see the effect of changing the acid-base environment without also changing the metal. The equations provide a chemical explanation for amphoterism rather than relying on a label.
Aluminium hydroxide may appear as a precipitate in qualitative ionic analysis; excess strong base can dissolve it under suitable conditions. A paper question may give observations such as a white solid forming and then disappearing as more hydroxide is added. Interpreting the sequence requires identifying a species change, not just ‘more soluble when more water is present’.
Neither an aluminium salt solution nor an aluminium hydroxide mixture should be treated as harmless because the metal is common in cookware. The chemical environment and laboratory conditions determine hazard and reaction rate. The educational goal is reasoning from the species and balanced net transformations.
Ask the student: Which formula summarises the amphoteric dissolution of Al(OH)₃ in excess OH⁻?
Evidence of understanding: Al(OH)₃ + OH⁻ → [Al(OH)₄]⁻.
9. Why silicon dioxide is acidic but not an ordinary soluble acid
Silicon dioxide forms an extended covalent network in familiar quartz-like structures. Its network is not made of small isolated SiO₂ molecules moving independently through a molecular liquid under normal conditions. This giant structure contributes to its high melting temperature and resistance to simple dissolution in water.
SiO₂ is an acidic oxide in the Period 3 classification because it can react with strong bases under appropriate conditions to form silicate species. An illustrative overall reaction is SiO₂ + 2NaOH → Na₂SiO₃ + H₂O, with conditions specified appropriately for the particular system.
Crucially, SiO₂ does not react with water to form a concentrated solution of a simple ‘silicic acid’ in the manner sulfur(VI) oxide can form sulfuric acid. A student who equates acidic oxide with ‘readily dissolves in water and makes the liquid acidic’ will get this example wrong.
The acid-base label describes chemical reaction tendencies; it is not a universal solubility label. The difference between MgO, Al₂O₃ and SiO₂ is therefore better understood through reactions with suitable acid or base and through the bonding structure, not by observing which powder disappears fastest in water.
Ask the student: Why can SiO₂ count as acidic even though it does not readily react with water?
Evidence of understanding: It reacts with sufficiently strong bases under suitable conditions to give silicates; acid/base character is not identical to water solubility.
10. Move right to phosphorus(V) oxide and sulfur(VI) oxide
Phosphorus(V) oxide, commonly written P₄O₁₀, reacts with water to form phosphoric acid in the familiar overall equation P₄O₁₀ + 6H₂O → 4H₃PO₄. Sulfur(VI) oxide SO₃ reacts with water to produce sulfuric acid: SO₃ + H₂O → H₂SO₄. Both are classed as acidic oxides.
These reactions show how non-metal oxides can form acids in water. But not every acidic oxide behaves with identical rate, heat evolution or molecular structure. Phosphorus(V) oxide and sulfur(VI) oxide have their own structural and physical details, and water reactions can be strongly exothermic.
The balanced P₄O₁₀ equation is worth auditing: four phosphorus atoms appear on each side, oxygen totals sixteen after six water molecules are included, and twelve hydrogen atoms match four H₃PO₄ molecules. The SO₃ equation is balanced one-to-one in the simplified model.
No student should be invited to put these reagents in water at home. Their real reactions can be dangerous. The tutor’s job is to connect formula, oxidation number and acid-forming outcome on paper, not provide apparatus instructions.
Ask the student: Which acids correspond to P₄O₁₀ and SO₃ under their familiar water-reaction models?
Evidence of understanding: Phosphoric acid H₃PO₄ and sulfuric acid H₂SO₄, respectively.
11. Relate the oxide trend to bonding and structure
From sodium and magnesium toward silicon, phosphorus and sulfur, electronegativity differences and the nature of chemical bonding change. The named metal oxides have substantial ionic character, while the non-metal oxides are represented by covalent bonding. Aluminium oxide lies in a region where polarisation and covalent contribution complicate a simplistic purely ionic picture.
A giant ionic lattice and a giant covalent network are both extended structures, but their electrostatic bonding descriptions differ. MgO is commonly treated as a lattice of Mg²⁺ and O²⁻ ions. SiO₂ has a network of Si–O covalent bonds; its formula expresses a ratio of silicon and oxygen atoms across that network.
P₄O₁₀ is often represented as a molecular oxide with discrete covalent units, while sulfur(VI) oxide may have different condensed-phase structures depending on conditions. For school acid-base classifications, the chemical equation and specified substance remain the decisive evidence; one should not assume every non-metal oxide is a simple gaseous molecule.
The interplay of structure and chemical behaviour is the deeper Period 3 insight. Across the named oxides, increasing oxidation states and changing bonding correlate with the acid/base shift, but neither oxidation state nor simple bond type alone is a complete general law for all possible compounds.
Ask the student: Why is SiO₂ described as a giant covalent network rather than an ionic solid like MgO?
Evidence of understanding: Its common structure has extended covalent Si–O bonds, whereas MgO is represented as an ionic lattice.
12. Separate acidity of an oxide from pH of a suspension
An oxide can be called basic, acidic or amphoteric based on its chemical reaction tendencies with acids and bases. This is distinct from reporting a numerical pH of the dry solid. pH is conventionally defined for an aqueous environment; writing ‘dry Al₂O₃ has pH seven’ without specifying a solution is not a valid application.
A dispersion of insoluble SiO₂ in pure water may not show the strong acidity one would expect from directly dissolving a strong acid. That does not remove the material’s classification as an acidic oxide in the reactions taught. Similarly, the limited solubility of Mg(OH)₂ affects a measured suspension differently from a highly soluble NaOH solution.
Students should identify what the test measures. A pH indicator reports the state of an aqueous phase, while an acid-base classification may be established through a solid’s reaction with a supplied reagent. One cannot use a colour strip in an unspecified dry mixture to determine a universal oxide pH.
This distinction also matters for aluminium oxide. Its amphoteric nature is demonstrated by reaction with both acid and strong base, not by an intermediate neutral indicator reading. A neutral-looking suspension is not by itself evidence of amphoterism.
Ask the student: Does ‘amphoteric’ mean aluminium oxide has pH exactly seven as a dry solid?
Evidence of understanding: No. It means it can react with acid and strong base under suitable conditions.
13. Catch equations and exceptions that cause errors
One familiar error is writing Al₂O₃ + H₂O → 2Al(OH)₃ as though ordinary aluminium oxide simply reacts with water like sodium oxide. In the standard named Period 3 table Al₂O₃ does not show an analogous easy water reaction. A similar error is inventing a direct SiO₂ + H₂O reaction to a strong acid.
A second error is treating MgO as amphoteric because aluminium lies nearby in Period 3. Each oxide needs its own reaction evidence. A third is failing to balance P₄O₁₀ with six water molecules, or using P₂O₅ without clarifying formula conventions. The official 2027 syllabus explicitly writes P₄O₁₀.
A fourth error is writing an amphoteric sodium hydroxide reaction without ensuring atoms and charge balance. For the aqueous aluminium complex, Al₂O₃ + 2OH⁻ + 3H₂O → 2[Al(OH)₄]⁻ is a useful balanced model. Students should not switch to a different aluminium species halfway through the calculation without notice.
Correction begins with classification and only then an equation. Ask what the oxide’s structure is, which reagent is supplied, whether water participates, and what products the model permits. A correct balanced equation with inappropriate conditions may still be chemically misleading.
Ask the student: What is the problem with claiming SiO₂ readily forms a strong acid just by standing in water?
Evidence of understanding: Silicon dioxide is an acidic oxide but its giant structure does not react readily with water in that simple way.
14. Transfer to an unfamiliar oxide without memorising the Period 3 list
Suppose an invented oxide X dissolves in acid and in excess aqueous NaOH, forming different soluble species, while showing little reaction with water alone. The supplied observations are consistent with amphoteric behaviour. Without the formula and full evidence, that classification does not uniquely identify X as Al₂O₃.
Now imagine oxide Y neutralises acid but has no comparable reaction with aqueous hydroxide under the specified conditions. That evidence supports a basic oxide classification in the school model. Oxide Z reacts with strong hydroxide and is not appreciably soluble in water, giving an acidic oxide possibility like SiO₂.
Students should use the reaction evidence instead of guessing an element from colour or solubility. A white oxide powder might be basic, acidic or amphoteric depending on its chemical identity. Observing that it is white supplies little information about its acid-base reaction behaviour.
A parent can ask a short transfer question: ‘What would an oxide have to react with before you called it amphoteric?’ The learner should answer ‘both acid and strong base under suitable conditions’ and supply balanced examples rather than saying ‘it is neither acidic nor basic’.
Ask the student: If an oxide reacts with acid and with excess aqueous NaOH, what classification is supported?
Evidence of understanding: Amphoteric, although that evidence does not uniquely identify the oxide.
Worked evidence: six oxides and two aluminium equations
This matrix deliberately separates what a substance is classified as, what it does with water and what it can do with acids or bases. Water reaction and acid/base oxide classification must not be treated as identical tests.
| Oxide or case | Oxidation state | Category/structure | Water or net reaction | Meaning |
|---|---|---|---|---|
| Na₂O | Na +1 | Basic, substantially ionic | Na₂O + H₂O → 2NaOH | Forms soluble strong base |
| MgO | Mg +2 | Basic, ionic lattice | MgO + H₂O → Mg(OH)₂ | Hydroxide sparingly soluble; acid neutralisation |
| Al₂O₃ | Al +3 | Amphoteric; extensive solid with ionic/covalent character | No facile water reaction | Reacts with acid and excess NaOH |
| SiO₂ | Si +4 | Acidic; giant covalent network | No facile water reaction | Can form silicate with strong base under suitable conditions |
| P₄O₁₀ | P +5 | Acidic; covalent oxide | P₄O₁₀ + 6H₂O → 4H₃PO₄ | Produces phosphoric acid |
| SO₃ | S +6 | Acidic; covalent oxide | SO₃ + H₂O → H₂SO₄ | Produces sulfuric acid |
| Al₂O₃ + acid | — | Amphoteric evidence | Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O | Acid reaction |
| Al₂O₃ + alkali | — | Amphoteric evidence | Al₂O₃ + 2OH⁻ + 3H₂O → 2[Al(OH)₄]⁻ | Strong aqueous base reaction |
The amphoteric category is justified by two different reaction partners. Al₂O₃ reacts with acid and with excess hydroxide; MgO is classified as basic and SiO₂ as acidic in the named 2027 Period 3 sequence. A substance’s response to plain water is a different observation from its response to a strong base.
Four transfer diagnostic cases
- An unknown oxide forms a salt in acid and a soluble hydroxo complex in excess NaOH: the evidence is consistent with amphoterism, but not a unique identification of aluminium oxide.
- An oxide does not react with water but does react with strong alkali: do not rule out an acidic oxide; SiO₂ supplies a named example.
- An oxide reacts to form a sparingly soluble hydroxide: account for both basic classification and solubility rather than claiming it must yield a concentrated alkali solution.
- A student claims all oxides of increasing oxidation number become more acidic in every chemical series: restrict the conclusion to named substances and reaction evidence instead of elevating one trend into a universal law.
Tutor checklist
- Confirm the child’s H2 Chemistry 9476 and the Section 5 Periodic Table topic in the applicable examination year.
- List exactly the named Na₂O, MgO, Al₂O₃, SiO₂, P₄O₁₀ and SO₃ syllabus oxides.
- Calculate the central-element oxidation states and distinguish ionic-to-covalent structure tendencies.
- Explain the difference between reaction with water and acid/base classification.
- Check the two amphoteric Al₂O₃ equations for both mass and charge balance.
- Identify Mg(OH)₂ as sparingly soluble rather than treating it as equivalent to soluble NaOH.
- Treat giant SiO₂ as acidic without inventing a simple water-to-strong-acid equation.
- Use an unseen oxide classification task that requires reaction evidence rather than colour or atomic-number guessing.
Frequently asked questions
Why is Al₂O₃ amphoteric?
It can react with acids and with sufficiently strong aqueous bases, such as NaOH, forming aluminium-containing products under suitable conditions.
Is MgO acidic or basic?
MgO is a basic oxide in the standard Period 3 comparison.
Why is SiO₂ acidic if it does not dissolve in water?
Acidic-oxide classification describes reaction with appropriate bases; it does not require readily producing an acidic aqueous solution just by adding water.
How does Al₂O₃ react with HCl?
A common balanced paper equation is Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O.
How does Al₂O₃ react with aqueous NaOH?
In a suitable excess hydroxide model, Al₂O₃ + 2OH⁻ + 3H₂O → 2[Al(OH)₄]⁻.
What does P₄O₁₀ produce with water?
It forms phosphoric acid in the balanced overall equation P₄O₁₀ + 6H₂O → 4H₃PO₄.
Does an acidic oxide necessarily give a low-pH suspension in plain water?
No. Water solubility and the pH of the surrounding aqueous phase are different from classification by reactions with acids and bases.
Is this included in 2027 H2 Chemistry?
Yes. SEAB syllabus 9476 Section 5 explicitly names these Period 3 oxides, their water reactions, and basic, acidic or amphoteric behaviour.
Continue with connected Periodic Table guides
- JC1 H2 Chemistry Tutor | Why Na⁺, Mg²⁺ and Al³⁺ Change Size
- JC1 H2 Chemistry Tutor | Ionisation Energy Exceptions
- Period 3 Oxides and Chlorides | Hougang H2 Chemistry Guide
- Hougang Chemistry Tuition and Tutor Library
For tuition support, bring the student’s exam year, school Periodic Table worksheet and any incorrect oxide-equation attempts. Confirm teacher, group size, lesson availability and location directly with the provider. This article does not promise any marks or tuition places.
Official syllabus and responsible scope
- SEAB: 2027 H2 Chemistry 9476, Section 5 Periodic Table
- SEAB: 2027 A-Level syllabus directory
- eduKateSG immutable Clementi small-group teaching reference
- Hougang Chemistry Tuition and Tutor Library
The 2027 H2 9476 Period 3 learning outcomes explicitly include oxide oxidation states, structures, reactions with water and acidic, basic and amphoteric behaviour with acids and sodium hydroxide (only) for the named oxides and hydroxides. Equations are classroom stoichiometric representations and are not instructions for using caustic oxides or strongly reactive aqueous preparations.