G3 Chemistry vocabulary is the bridge between what you see in an experiment and what happens to particles. If a student understands the difference between an atom, an ion and a molecule, balanced equations and bonding become more intelligible. If they can distinguish observation from explanation, practical and structured answers become stronger. This guide offers 200 clearly defined Chemistry terms for students preparing for Singapore’s 2027 SEC G3 Chemistry, with lessons drawn from everyday materials, laboratory work and environmental questions.

The official 2027 separate G3 Chemistry subject code is K324, with 6092 shown as the earlier reference code. It is not the same course as combined G3 Science (Physics, Chemistry) K326 or Science (Chemistry, Biology) K328. These 200 terms are an independent teaching glossary based on relevant topic areas, not a list officially prescribed by SEAB. Students should confirm their actual subject and examination year before selecting papers or revision books.

Quick answers:

• Start with matter, particles, bonding, equations and basic calculations before memorising reaction patterns.
• In a structured answer, link observation → particles or electrons → scientific mechanism.
• In practical work, record what you actually observe; do not replace evidence with what you expected.
• For organic Chemistry, distinguish names, functional groups, structures and reaction conditions.
• Study the K324 syllabus and school practical instructions alongside this glossary; a few linking terms give useful enrichment beyond immediate assessed detail.

1–10: Laboratory equipment and safe handling

1. hazard — Something capable of causing harm.
2. corrosive — Able to damage tissue or materials through chemical action.
3. flammable — Able to catch fire relatively easily.
4. toxic — Capable of causing harm through chemical exposure.
5. goggles — Protective eyewear used during laboratory work.
6. Bunsen burner — A laboratory gas burner for controlled heating.
7. test tube — A small glass vessel used for small-scale reactions.
8. beaker — A wide-mouthed container for holding or mixing liquids.
9. pipette — Instrument transferring a measured liquid volume.
10. burette — Graduated apparatus dispensing measured liquid volumes.

11–20: Measurements, uncertainty and experiments

11. precision — Closeness of repeated measurements to one another.
12. accuracy — Closeness of a measurement to the accepted value.
13. reliability — Dependability of results from suitable repeated work.
14. repeatability — Obtaining similar results when a method is repeated.
15. independent variable — Factor deliberately changed by the experimenter.
16. dependent variable — Factor measured as the response.
17. controlled variable — Factor deliberately kept the same.
18. titration — Technique measuring how much solution reacts with another.
19. end-point — Observed signal indicating the titration should stop.
20. meniscus — Curved liquid surface used when reading some apparatus.

21–30: Separation and solutions

21. solution — A homogeneous mixture of solute and solvent.
22. solvent — The liquid or other medium doing the dissolving.
23. solute — Substance being dissolved.
24. filtration — Separating insoluble solid from fluid using a filter.
25. residue — Material left on the filter.
26. filtrate — Fluid passing through the filter.
27. crystallisation — Forming solid crystals from a suitable solution.
28. distillation — Separating substances using vaporisation and condensation.
29. chromatography — Separating components according to how they move through a medium.
30. saturation — Condition in which no more solute dissolves at stated conditions.

31–40: Particles, substances and states

31. atom — Smallest particle of an element retaining its chemical identity.
32. element — Pure substance containing one kind of atom.
33. compound — Pure substance containing two or more elements chemically combined.
34. mixture — Substances combined without being chemically joined into one compound.
35. molecule — A discrete group of bonded atoms.
36. ion — Atom or group with net electrical charge.
37. solid — State with fixed shape and volume.
38. liquid — State with fixed volume and no fixed shape.
39. gas — State expanding to fill its container.
40. diffusion — Net spreading of particles through random movement.

41–50: Atomic structure

41. proton — Positively charged particle in an atomic nucleus.
42. neutron — Uncharged particle in an atomic nucleus.
43. electron — Negatively charged particle occupying space around a nucleus.
44. nucleus — Dense central part of an atom containing protons and neutrons.
45. proton number — Number of protons in an atom’s nucleus.
46. nucleon number — Total number of protons and neutrons in a nucleus.
47. isotope — Atoms of one element with different numbers of neutrons.
48. electron shell — A principal electron energy level in simplified atomic models.
49. valence electron — Electron in the outermost occupied shell.
50. electronic configuration — Arrangement of electrons in an atom or ion.

51–60: Chemical bonding and structures

51. ionic bond — Electrostatic attraction between oppositely charged ions.
52. covalent bond — Bond formed by sharing electron pairs between atoms.
53. metallic bond — Attraction between positive metal ions and delocalised electrons.
54. cation — Positively charged ion.
55. anion — Negatively charged ion.
56. electrostatic attraction — Force between opposite electric charges.
57. delocalised electron — Electron not confined to one particular atom or bond.
58. giant lattice — Extended regular arrangement of particles.
59. simple molecule — Small discrete group of covalently bonded atoms.
60. intermolecular force — Attraction between separate molecules.

61–70: Linking properties to structures

61. conductivity — Ability of a material to carry heat or electric current.
62. malleability — Ability to be shaped into sheets without breaking.
63. ductility — Ability to be drawn into wires.
64. melting point — Temperature at which solid and liquid coexist in equilibrium at stated pressure.
65. boiling point — Temperature when a liquid boils at stated pressure.
66. solubility — Amount of a solute that can dissolve under stated conditions.
67. hardness — Resistance of a material to scratching or indentation.
68. volatility — Tendency to vaporise readily.
69. electrical resistance — Opposition to electric current in a material or component.
70. brittleness — Tendency to break rather than bend.

71–80: Writing chemical reactions

71. reactant — Starting substance consumed or transformed in a reaction.
72. product — Substance formed by a reaction.
73. chemical equation — Symbolic statement showing reactants and products.
74. balanced equation — Equation showing equal numbers of each kind of atom on both sides.
75. coefficient — Number before a formula giving relative reaction amounts.
76. subscript — Small number within a formula showing atom counts.
77. formula — Symbols and numbers showing a substance’s composition.
78. state symbol — Notation such as (s), (l), (g) or (aq).
79. conservation of mass — Matter is not lost or created in an ordinary chemical reaction.
80. reversible reaction — Reaction proceeding in forward and reverse directions.

81–90: Chemical calculations

81. mole — SI unit for amount of substance.
82. molar mass — Mass of one mole of a substance.
83. relative atomic mass — Weighted relative mass of atoms of an element.
84. relative molecular mass — Sum of relative atomic masses in a molecule.
85. concentration — Amount of solute in a stated volume of solution.
86. molar volume — Volume occupied by one mole of gas at specified conditions.
87. percentage yield — Actual yield expressed as a percentage of theoretical yield.
88. limiting reagent — Reactant used up first, limiting product formed.
89. stoichiometry — Quantitative relationships between reactants and products.
90. amount of substance — Quantity measured in moles.

91–100: Acids, bases and neutralisation

91. acid — Substance producing hydrogen ions in aqueous solution.
92. alkali — A soluble base that produces hydroxide ions in water.
93. base — Substance that can neutralise an acid.
94. neutralisation — Reaction of an acid with a base to form salt and water in common aqueous cases.
95. pH — Scale indicating acidity or alkalinity of a solution.
96. indicator — Substance changing colour under specified chemical conditions.
97. salt — Ionic compound produced in reactions including neutralisation.
98. hydrogen ion — H⁺, responsible for characteristic acidity in water.
99. hydroxide ion — OH⁻, characteristic of aqueous alkalis.
100. acid strength — Degree of ionisation of an acid in water.

101–110: Qualitative analysis and observations

101. qualitative analysis — Identifying substances from their chemical behaviour.
102. precipitate — Insoluble solid formed in a solution reaction.
103. flame test — Using flame colour as a clue to certain ions.
104. gas test — Procedure identifying a gas by a characteristic observation.
105. effervescence — Visible bubbling when gas is released from a liquid.
106. chloride test — Chemical procedure used to identify chloride ions.
107. sulfate test — Chemical procedure used to identify sulfate ions.
108. ammonium ion — NH₄⁺, identifiable using appropriate laboratory tests.
109. aqueous solution — A solution in which water is the solvent.
110. reagent — A chemical used to test or cause a reaction.

111–120: Oxidation and reduction

111. redox — Reaction involving oxidation and reduction together.
112. oxidation — Loss of electrons or increase in oxidation state; also oxygen gain in some contexts.
113. reduction — Gain of electrons or decrease in oxidation state; also oxygen loss in some contexts.
114. oxidising agent — Species that causes oxidation and is itself reduced.
115. reducing agent — Species that causes reduction and is itself oxidised.
116. electron transfer — Movement of electrons from one species to another.
117. oxidation state — Formal number used to track electron changes.
118. combustion — Reaction involving burning in oxygen.
119. corrosion — Chemical or electrochemical deterioration of material.
120. rusting — Corrosion of iron producing hydrated iron oxides.

121–130: Electrolysis and electrochemical cells

121. electrolysis — Chemical change driven by electric current through an electrolyte.
122. electrolyte — Substance that conducts by movement of ions when molten or in solution.
123. anode — Electrode where oxidation occurs.
124. cathode — Electrode where reduction occurs.
125. electrode — Conductor through which current enters or leaves an electrolyte.
126. selective discharge — Preferential reaction of certain ions at electrodes.
127. electroplating — Depositing a metal coating by electrolysis.
128. molten electrolyte — An ionic substance melted so ions can move.
129. inert electrode — Electrode that normally does not participate in the intended reaction.
130. fuel cell — Device converting chemical reaction energy directly into electrical energy.

131–140: The Periodic Table and patterns

131. Periodic Table — Arrangement of elements by increasing proton number.
132. group — Vertical column of related elements in the Periodic Table.
133. period — Horizontal row of elements in the Periodic Table.
134. alkali metal — Group 1 metal with characteristic reactive behaviour.
135. halogen — Group 17 element.
136. noble gas — Group 18 element with a stable outer electron configuration.
137. transition element — Element of the transition block with characteristic metallic properties.
138. metallic character — Extent to which an element behaves like a metal.
139. reactivity series — Ranking of metals by their tendency to react.
140. periodic trend — Regular change in properties across the Periodic Table.

141–150: Energy changes in reactions

141. exothermic — Releasing energy to the surroundings overall.
142. endothermic — Taking in energy from the surroundings overall.
143. enthalpy change — Difference in enthalpy between products and reactants.
144. activation energy — Minimum energy barrier for a reaction pathway.
145. energy profile — Diagram displaying energy changes during reaction.
146. bond breaking — Process requiring energy to separate bonded atoms.
147. bond making — Process releasing energy as bonds form.
148. energy transfer — Movement of energy between a system and surroundings.
149. reaction energy — Energy change associated with a chemical reaction.
150. thermal decomposition — Breakdown of a compound caused by heating.

151–160: Rates of reaction

151. rate of reaction — Speed at which reactants are used or products formed.
152. collision theory — Explanation of reaction rate using particle collisions.
153. catalyst — Substance increasing reaction rate without being used up overall.
154. enzyme — Biological catalyst.
155. frequency of collisions — How often reacting particles collide.
156. surface area — Exposed area available for collisions.
157. particle size — Size of pieces affecting exposed area and rate.
158. temperature — Measure influencing particle energies and collision effectiveness.
159. pressure — Force per area; gas pressure can affect collision frequency.
160. effective collision — Collision with sufficient energy and suitable conditions to react.

161–170: Organic chemistry: fuels and hydrocarbons

161. hydrocarbon — Compound containing only carbon and hydrogen.
162. alkane — Saturated hydrocarbon with single carbon-carbon bonds.
163. alkene — Unsaturated hydrocarbon with at least one carbon-carbon double bond.
164. methane — CH₄, the simplest alkane and main component of natural gas.
165. ethene — C₂H₄, a simple alkene with a carbon-carbon double bond.
166. crude oil — Naturally occurring mixture containing many hydrocarbons.
167. fractional distillation — Separating a mixture by differing boiling ranges.
168. cracking — Breaking larger hydrocarbons into smaller molecules.
169. saturated — Containing no carbon-carbon multiple bonds in this hydrocarbon context.
170. unsaturated — Containing at least one carbon-carbon multiple bond.

171–180: Alcohols, acids, esters and polymers

171. ethanol — A two-carbon alcohol used in fuels and other applications.
172. alcohol — Organic compound containing a hydroxyl functional group.
173. carboxylic acid — Organic compound containing the carboxyl functional group.
174. ester — Organic compound formed in reactions such as an alcohol with a carboxylic acid.
175. polymer — Very large molecule made from repeated units.
176. monomer — Small molecule used to build polymers.
177. polymerisation — Reaction joining monomers into a polymer.
178. addition polymerisation — Joining unsaturated monomers without losing small molecules.
179. condensation polymerisation — Polymer formation accompanied by elimination of small molecules.
180. biodegradable — Capable of being broken down by biological processes under suitable conditions.

181–190: Air quality, emissions and society

181. air pollutant — Substance in air present at levels capable of causing harm.
182. particulate matter — Tiny solid or liquid particles suspended in air.
183. carbon monoxide — Poisonous gas produced by incomplete combustion of carbon fuels.
184. carbon dioxide — Gas produced in many combustion reactions and contributing to warming.
185. sulfur dioxide — Air pollutant from burning sulfur-containing fuels.
186. nitrogen oxides — Reactive nitrogen-oxygen gases contributing to air pollution.
187. acid rain — Precipitation made unusually acidic by atmospheric pollutants.
188. greenhouse effect — Warming caused by gases absorbing and re-emitting infrared radiation.
189. carbon footprint — Estimated greenhouse gas emissions attributed to an activity.
190. air quality — Condition of the air in relation to pollutants and health.

191–200: Examination instructions and thinking verbs

191. define — Give the precise meaning of a scientific term.
192. state — Give the requested fact without unnecessary explanation.
193. describe — Give relevant features or observations.
194. explain — Show why an observation or process occurs.
195. suggest — Propose a reasonable response based on given knowledge.
196. predict — Use principles and information to anticipate an outcome.
197. deduce — Draw a logical conclusion from available information.
198. calculate — Find a numerical result using a valid method.
199. evaluate — Judge evidence, uncertainty or the value of a method.
200. plan — Design a suitable investigation or sequence of steps.

How 200 Chemistry terms become understanding instead of memorisation

Example 1: Why does molten sodium chloride conduct but the solid does not?

Solid sodium chloride contains ions arranged in a lattice. They are not free to move through the solid, so it does not conduct electric current in the usual classroom arrangement. When molten, the ions become mobile and carry charge. A useful explanation therefore names mobile ions and their movement, rather than saying that the substance “has electricity.” A metal such as copper conducts by mobile delocalised electrons, which is a different mechanism.

Example 2: A balanced equation shows conservation, not just neat notation

For magnesium reacting with oxygen, the balanced equation is 2Mg + O₂ → 2MgO. Both sides contain two Mg atoms and two O atoms. The large number in front is a coefficient; the small number in O₂ is a subscript. Changing subscripts to balance an equation would change which substance is being represented. This connects vocabulary to the conservation of matter and later mole calculations.

Example 3: An acid–alkali reaction

Hydrochloric acid reacting with sodium hydroxide gives sodium chloride and water: HCl + NaOH → NaCl + H₂O. The acid supplies hydrogen ions; the alkali supplies hydroxide ions in aqueous solution. They combine to form water. The solution’s pH depends on what is left after the reaction; do not assume every mixture becomes pH 7 without considering the reacting amounts and conditions.

Example 4: Oxidation and reduction must happen together

When zinc transfers electrons to copper(II) ions, zinc is oxidised and the copper(II) ions are reduced. Remember oxidation = electron loss and reduction = electron gain for this kind of explanation. An oxidising agent accepts electrons and is itself reduced. Naming the role without stating electron movement is a common incomplete answer.

Example 5: A catalyst changes rate, not the identity of the chemical equation

A catalyst offers a reaction pathway with lower activation energy, allowing a larger fraction of collisions to be effective at the same conditions. It is not consumed overall. For rate experiments, changed variables such as concentration, temperature and exposed surface area must be considered against controlled conditions and the measurement technique.

Example 6: Why Chemistry belongs in environmental questions

Crude oil is a mixture of hydrocarbons. Fractional distillation separates it into useful fractions; combustion can also produce pollutants. Plastics are valuable materials but may contribute to waste challenges. Real environmental decisions require comparing performance, production, reuse, disposal and total effects. Chemical vocabulary helps distinguish a scientifically supported explanation from a slogan.

Reading the 2027 SEC K324 syllabus correctly

SEAB’s syllabus groups Chemistry into three main sections: Matter — Structures and Properties, Chemical Reactions, and Chemistry in a Sustainable World. These include experimental Chemistry, particles, bonding, calculations, acids and bases, qualitative analysis, redox, periodic patterns, energetics, rates, organic Chemistry and air quality. K324 also assesses experimental skills, not only written recall. The school’s current curriculum and official exam document decide which outcomes and level of detail must be mastered.

For the three-paper structure and the differences between K324 and combined Science, read our Punggol Secondary 4 SEC 2027 Chemistry K324 parent guide.

Four-week vocabulary-to-application programme

1. Week 1 — Foundations: select 50 terms from apparatus, particles, atomic structure, bonding and properties. Sketch ions, atoms and particles, and explain what each diagram can and cannot show.
2. Week 2 — Reactions: learn the language of equations, mole calculations, acids, analysis and redox. Balance equations and write the reason for each step.
3. Week 3 — Patterns: revisit electrolysis, the Periodic Table, energy changes and rates. Use unfamiliar experiments and identify the underlying principle.
4. Week 4 — Wider chemistry: organic chemistry, polymers, air quality and command words. Practise mixed structured responses and practical observations, revisiting errors from earlier weeks.

This schedule is deliberately selective: a student should prioritise the terms relevant to their current chapter, then revisit them repeatedly in different forms. Seeing a word once is recognition; explaining an unfamiliar observation with it is transfer.

Common Chemistry language errors

• Atom versus ion: an ion carries net electrical charge; a neutral atom does not.
• Molecule versus compound: a molecule is a discrete bonded group; not every compound consists of discrete molecules.
• Anode versus cathode: oxidation occurs at the anode; reduction at the cathode. Their signs depend on cell type.
• Concentrated versus strong acid: concentration describes amount per volume; strength describes extent of ionisation.
• Observation versus inference: “white precipitate forms” is an observation; the identity of an ion must be supported by an appropriate test.
• Amount versus rate: a reaction can produce the same overall amount at a different rate under changed conditions.

Frequently asked questions

Is this an official SEAB G3 Chemistry vocabulary list?

No. It is an original 200-term explanation bank. The official learning outcomes, papers and practical instructions remain the governing reference.

Is G3 Chemistry K324 the same as O-Level Chemistry 6092?

SEAB shows 6092 as the reference code for 2026 and earlier, while 2027 G3 Chemistry is K324. Check the current K324 syllabus rather than assuming all older materials are interchangeable.

Is G3 Chemistry the same as combined Science Chemistry?

No. The subject combinations and assessment requirements differ. Confirm the registered K-code before using this glossary as an exam checklist.

What should a student do when they do not know a command word?

Read the command word first. State asks for a concise fact, while explain asks for a reason or mechanism; deduce requires reasoning from supplied evidence.

Do students need to memorise every apparatus word?

They should recognise equipment and understand its safe supervised use and measurement purpose. Actual experimental competence cannot be replaced by definitions.

Where can Chemistry appear in everyday life?

Cooking, rusting, household materials, air pollution, batteries and recycling all connect to chemical ideas. Use these as conversation starters, not unsupervised home chemistry experiments.

Official sources and next reading

Check the official SEAB 2027 SEC G3 school-candidate syllabus index and open Chemistry K324 from that page for the precise subject content. Read our guide to checking the correct 2027 K-code before purchasing assessment books. The G3 Chemistry tuition subject-code guide explains how subject-specific learning support should begin with the student’s actual course and baseline.

eduKate Punggol, November 2026. Independent glossary for Chemistry learning. Always defer to official SEAB and school documents for examination requirements, practical safety and current syllabus changes.