Athens Academy Islamabad · Chemistry Grade 10 · Unit 1

Athens Academy Islamabad · Chemistry Grade 10 · Unit 1 · History of Chemistry

Board: FBISE Grade: 10 Unit: 1 Exam Session: Exam 2027

How this unit is examined There are no numericals, formulae or equations in this unit. Almost every mark comes from recall — names matched to contributions, and definitions matched to branches. That makes it the easiest unit in the paper to score full marks in, and the easiest to throw marks away in by guessing. Learn the two name tables and the branches table, and you have covered most of the unit's weight.

01What Chemistry Is

★ Definition Chemistry is the branch of science that deals with the composition, structure, properties and changes of matter, and with the energy changes that accompany those changes.

Every part of that definition is examinable, so read it as four separate ideas:

Composition	What a substance is made of — which elements, and in what proportion.
Structure	How the particles of that substance are arranged and joined.
Properties	How the substance behaves — its colour, melting point, reactivity, and so on.
Changes	How one substance turns into another, and the energy absorbed or released.

Memory hook: chemistry asks four questions about any substance — what is it made of, how is it put together, how does it behave, and how does it change? Composition, Structure, Properties, Changes. Say them in that order every time and the definition writes itself.

Origin of the word

The English word chemistry comes from alchemy, which comes from the Arabic al-kimiya. The Arabic term is generally traced further back to kimiya or to the old Egyptian word kemet, meaning "black land" — a reference to the dark, fertile soil of the Nile.

Examiner tip: the chain kemet / kimiya → al-kimiya → alchemy → chemistry is a very common one-mark MCQ. Learn it as one chain, not as four separate words, and you will never put the arrows the wrong way round.

Figure 1.1 — Chemistry did not replace alchemy overnight. It grew out of alchemy once experiment and measurement replaced secrecy.

02Alchemy: The Ancestor of Chemistry

★ Definition Alchemy was an early practice, part craft and part mysticism, whose practitioners tried to change ordinary metals into gold and to find a substance that would give unending life.

The three aims of the alchemists

Aim	What they wanted
Transmutation	To convert base metals such as lead, copper and iron into gold or silver.
Philosopher's stone	An imagined substance believed to bring about that conversion.
Elixir of life	An imagined liquid believed to cure every disease and grant long life.

Why alchemy failed

It was based on belief and mysticism, not on evidence.
Work was kept secret and written in code, so results could not be checked or repeated.
Nothing was measured or weighed, so no reliable conclusions could be drawn.
Its central aim was impossible: one element cannot be turned into another by a chemical reaction.

What alchemy nevertheless gave us

Alchemists were poor scientists but skilled practical workers. Over centuries they developed the apparatus and the separation techniques that laboratories still use today:

Technique	What it does
Distillation	Separates liquids by boiling and condensing the vapour.
Crystallisation	Obtains a pure solid from its solution.
Sublimation	Purifies solids that pass straight from solid to vapour.
Filtration	Separates an insoluble solid from a liquid.
Calcination	Strongly heats a substance in air to decompose it.

Figure 1.2 — Distillation in an alchemist's workshop: liquid is boiled in the retort, the vapour travels down the neck and cools, and pure liquid collects in the receiver. The idea is unchanged in a modern laboratory.

Alchemy compared with chemistry

Point of comparison	Alchemy	Chemistry
Basis	Belief, mysticism, tradition	Observation and evidence
Method	Trial and error, kept secret	Controlled experiment, published openly
Measurement	Little or none	Central; quantities are measured
Aim	Gold and eternal life	To understand matter and its changes
Result	Failed in its aims	Reliable, repeatable knowledge

Examiner tip: this comparison table is one of the two most likely short questions in the whole unit. Learn it by the five comparison points — basis, method, measurement, aim, result — so that whatever number of points the question asks for, you can supply them in order.

Exam trap Do not write that alchemy contributed nothing. Its aims failed, but it handed chemistry its apparatus and its separation techniques — distillation, crystallisation, sublimation, filtration and calcination. A question asking "what did chemistry gain from alchemy?" is asking for exactly those, not for a criticism.

03Contributions of Muslim Scientists

Between roughly the eighth and eleventh centuries, Muslim scholars turned alchemy into something much closer to a science. Their decisive change was insisting on experiment and on written, repeatable procedure instead of secrecy.

Scientist	Remembered for
Jabir bin Hayyan (Geber)	Called the Father of Chemistry. Introduced systematic experiment and laboratory procedure; prepared strong acids including nitric and sulphuric acid; refined distillation, crystallisation and sublimation; described and improved laboratory apparatus.
Al-Razi (Rhazes)	Classified substances into mineral, vegetable and animal (and further into bodies, spirits, stones and salts). Prepared and described alcohol. Applied chemistry to medicine and wrote careful laboratory descriptions.
Al-Biruni	Determined the density (specific gravity) of many metals and precious stones with remarkable accuracy — an early example of chemistry done by measurement.
Ibn Sina (Avicenna)	Wrote Al-Qanun fil-Tibb (The Canon of Medicine), used in Europe for centuries. Rejected the alchemists' claim that one metal could be transmuted into another.
Al-Kindi	Also rejected transmutation. Worked on the distillation of perfumes and essential oils.

Memory hook: group them by what each one contributed — Jabir gave the method, Al-Razi gave the classification, Al-Biruni gave the measurement, and Ibn Sina and Al-Kindi gave the rejection of transmutation. Two names share the last one, which is why examiners like to ask it.

Exam trap Jabir bin Hayyan is the Father of Chemistry. Antoine Lavoisier is the Father of Modern Chemistry. Examiners set both in the same paper precisely because students mix them up. The word that decides the answer is "Modern" — read the question twice before you write the name.

04Contributions of Modern Chemists

Scientist	Remembered for
Robert Boyle	Gave the modern idea of an element as a substance that cannot be broken down further. Stated Boyle's law relating the pressure and volume of a gas. Argued that chemistry should stand apart from alchemy and from medicine.
Antoine Lavoisier	Called the Father of Modern Chemistry. Established the law of conservation of mass by careful weighing, and showed that burning is a reaction with oxygen — which disproved the phlogiston theory.
John Dalton	Proposed the atomic theory: matter is made of indivisible atoms, and atoms of the same element are alike in mass and properties.
Dmitri Mendeleev	Arranged the known elements into the first useful periodic table, in order of atomic mass, and left gaps for elements not yet discovered.
Marie Curie	Pioneered the study of radioactivity and discovered the elements polonium and radium.

Key idea Chemistry became a true science when the balance entered the laboratory. Lavoisier's habit of weighing everything before and after a reaction is what separated chemistry from alchemy — not any single discovery.

Common error: writing that Mendeleev arranged the elements by atomic number. He arranged them by atomic mass; atomic number came later. One word, one mark.

05Branches of Chemistry

Figure 1.3 — The main branches of chemistry. The upper row are the core branches; the lower row are applied branches, which grow out of the core.

Branch	What it studies
Physical chemistry	The physical behaviour of matter and the energy changes in reactions — rates, equilibrium, structure.
Inorganic chemistry	All elements and their compounds except most compounds of carbon — metals, minerals, salts.
Organic chemistry	Compounds of carbon and hydrogen and their derivatives — fuels, plastics, medicines.
Analytical chemistry	Finding out what a sample contains (qualitative) and how much of it is present (quantitative).
Biochemistry	The chemical reactions and molecules inside living organisms — proteins, enzymes, DNA.
Industrial chemistry	Manufacturing chemicals on a large scale — fertilisers, cement, soaps, acids.
Environmental chemistry	Chemical processes in air, water and soil, including pollution and its control.
Nuclear chemistry	Changes in the nucleus — radioactivity, nuclear energy, medical isotopes.

Exam trap — the two pairs students confuse Analytical vs industrial: analytical tests and measures a sample; industrial manufactures in bulk. Testing a bag of urea for purity is analytical; making that urea at the plant is industrial.
Organic vs biochemistry: organic covers all carbon compounds, living or not — the petrol in a rickshaw is organic chemistry; biochemistry covers only the chemistry happening inside living things.

06The Scientific Method

The scientific method is the orderly procedure that replaced the alchemists' guesswork. It is what makes a claim in chemistry checkable by anyone, anywhere.

Figure 1.4 — The scientific method. The return arrow is the important part: a hypothesis that fails is changed, not defended.

Step	Meaning
Observation	Noticing and recording a fact carefully.
Hypothesis	A tentative explanation that can be tested.
Experiment	A controlled test that supports or disproves the hypothesis.
Theory	A hypothesis that has survived repeated testing and explains many observations.
Law	A statement, often mathematical, of a relationship that always holds under stated conditions.

Memory hook: O–H–E–T–L — "Only Honest Experiments Teach Laws." Five letters, five steps, in order.

Exam trap A theory is not "a guess" and not "something not yet proved". A theory explains why something happens; a law states what happens without explaining it. Dalton's atomic theory explains; the law of conservation of mass states.

07Chemistry in Daily Life and Careers

Field	How chemistry is used
Medicine	Designing, making and testing drugs; diagnostic tests; disinfectants.
Agriculture	Fertilisers such as urea, pesticides, and soil testing.
Food	Preservation, packaging, nutrition, and testing food for adulteration.
Textiles	Synthetic fibres, dyes, bleaching and finishing.
Energy and fuels	Refining petroleum, natural gas, batteries and cells.
Environment	Water treatment, control of air pollution, waste management.
Forensics	Chemical analysis of evidence in criminal investigation.

In Pakistan this is not abstract. Urea and other fertilisers are manufactured at plants such as Fauji Fertilizer; rock salt is mined and purified at Khewra; municipal water in Karachi and Lahore is treated chemically before it reaches the tap; and cement, sugar and textile mills across Punjab and KPK all employ chemists for quality control.

Careers that grow out of this subject

Analytical chemist — testing samples in food, drug or water laboratories.
Pharmacist / pharmaceutical chemist — formulating and checking medicines.
Chemical engineer — designing and running industrial plants.
Agricultural chemist — soil and fertiliser work.
Forensic chemist — laboratory analysis for investigation.
Teacher or researcher — schools, colleges and research institutes.

Worked Examples

This unit has no numericals, so the marks are won by structure. Each example below shows how to lay an answer out so that the examiner can find every mark without hunting for it.

Worked Example 1 · Short question · 3 marks

Differentiate between alchemy and chemistry on any three points.

Given: Two practices to be compared: alchemy and chemistry.
Required: Three points of difference.
Approach: A "differentiate" question with three marks wants three paired statements — one about each side for every point. Choose three comparison points from the five learned: basis, method, measurement, aim, result.
Steps: 1. Basis — alchemy rested on belief and mysticism; chemistry rests on observation and evidence.
2. Measurement — alchemists measured little or nothing; in chemistry, quantities are measured and are central.
3. Aim — alchemy sought gold and eternal life; chemistry seeks to understand matter and its changes.
Result: Three complete pairs, each one worth one mark.

∴ Answer: alchemy and chemistry differ in basis, in measurement and in aim, as set out above.

Worked Example 2 · Short question · 3 marks

Why is Jabir bin Hayyan called the Father of Chemistry, while Lavoisier is called the Father of Modern Chemistry?

Given: Two titles that sound similar and are awarded to two different scientists.
Required: The reason behind each title, kept clearly apart.
Approach: Answer in two separate sentences, one per scientist. Never blend them into one sentence — a blended answer usually loses a mark because the examiner cannot tell which claim belongs to whom.
Steps: 1. Jabir bin Hayyan — he introduced systematic experiment and written laboratory procedure, prepared strong acids such as nitric and sulphuric acid, and refined distillation, crystallisation and sublimation. He therefore turned a secretive craft into a practised discipline.
2. Lavoisier — he established the law of conservation of mass by careful weighing and showed that burning is a reaction with oxygen, disproving the phlogiston theory. He therefore put chemistry on a quantitative footing.
Result: Two distinct reasons, one for the method, one for the measurement.

∴ Answer: Jabir bin Hayyan is Father of Chemistry for founding experimental method; Lavoisier is Father of Modern Chemistry for making chemistry quantitative.

Worked Example 3 · Application · 4 marks

A laboratory in Rawalpindi tests a sample of tap water and reports the exact amount of each dissolved salt it contains. A nearby factory then uses that report to design a large treatment plant. Name the branch of chemistry involved at each stage and justify your choice.

Given: Stage 1 — a water sample is tested and the amount of each salt is reported. Stage 2 — a large-scale treatment plant is designed and built.
Required: The branch of chemistry at each stage, with a justification for each.
Approach: Match the verb in the question to the definition of the branch. "Tests and reports how much" points to one branch; "large scale" points to another. Environmental chemistry is also relevant because the substance being studied is water.
Steps: 1. Stage one — analytical chemistry. Analytical chemistry finds out what a sample contains and how much of it is present. Reporting the exact amount of each salt is a quantitative analysis, so it belongs here.
2. Stage two — industrial chemistry. Industrial chemistry deals with carrying out chemical processes on a large scale. Designing a treatment plant is manufacturing scale, not testing scale.
3. Overlap — environmental chemistry. Because the material under study is the water supply, the whole task also sits within environmental chemistry, which covers chemical processes in air, water and soil, and their treatment.
Result: Analytical at the testing stage, industrial at the plant stage, with environmental chemistry running across both.

∴ Answer: stage 1 is analytical chemistry (it measures how much is present); stage 2 is industrial chemistry (it works at manufacturing scale); both fall under environmental chemistry because the subject is water quality.

Worked Example 4 · Short question · 3 marks

List the steps of the scientific method in order, and state clearly how a theory differs from a law.

Given: Two tasks in one question: an ordered list, and a distinction.
Required: The five steps in the correct order, plus one clean sentence of difference.
Approach: Do the listing first and keep it to one line — order is what earns the mark, not description. Then give the difference in a single "explains vs states" sentence and anchor it with one example of each.
Steps: 1. The order — observation → hypothesis → experiment → theory → law. If the experiment disagrees with the hypothesis, the hypothesis is revised and tested again.
2. The distinction — a theory explains why something happens; a law states what happens, without explaining it.
3. The examples — Dalton's atomic theory explains what matter is made of; the law of conservation of mass simply states that mass is unchanged in a reaction.
Result: Correct sequence, correct distinction, and one worked example of each type.

∴ Answer: the order is observation, hypothesis, experiment, theory, law; a theory explains why, whereas a law states what happens.

Key Terminology

Term	Meaning
Chemistry	The study of the composition, structure, properties and changes of matter.
Alchemy	The early practice aimed at turning base metals into gold and finding an elixir of life.
Transmutation	The supposed conversion of one metal into another, especially into gold.
Philosopher's stone	The imagined substance believed to cause transmutation.
Elixir of life	The imagined liquid believed to cure all disease and prolong life.
Element	A pure substance that cannot be broken down into simpler substances chemically.
Distillation	Separation of liquids by boiling and then condensing the vapour.
Calcination	Strong heating of a substance in air in order to decompose it.
Hypothesis	A testable, tentative explanation of an observation.
Theory	A well-tested explanation supported by much evidence.
Law	A statement of a relationship that always holds under stated conditions.
Radioactivity	The spontaneous emission of radiation from unstable nuclei.

60-Minute Revision Checklist

Work down the list with the notes closed. Tick only what you can actually say aloud; go back and read the section again for anything you cannot.

❑ I can define chemistry in one sentence, with all four parts.

❑ I can name the four parts: composition, structure, properties, changes.

❑ I can trace the word from kemet / kimiya to chemistry.

❑ I can define alchemy in one sentence.

❑ I can state the three aims of the alchemists.

❑ I can give four reasons alchemy failed.

❑ I can list five techniques alchemy left behind.

❑ I can label the parts of a distillation set-up.

❑ I can fill the alchemy-vs-chemistry table from memory.

❑ I can name five Muslim scientists with one contribution each.

❑ I know who is called the Father of Chemistry.

❑ I know who is called the Father of Modern Chemistry.

❑ I can state what Boyle, Dalton, Mendeleev and Curie each did.

❑ I know Mendeleev used atomic mass, not atomic number.

❑ I can name eight branches and define each in one line.

❑ I can separate analytical from industrial chemistry.

❑ I can separate organic chemistry from biochemistry.

❑ I can list the steps of the scientific method in order.

❑ I can explain the difference between a theory and a law.

❑ I can give six uses of chemistry in daily life.

❑ I can name four careers that need chemistry.

❑ I have written out both name tables without looking.

Final word from Athens Academy This unit is a gift, and you should treat it like one. There is nothing here to calculate and nothing to derive — only a short list of names, a short list of branches, and five steps of a method. Sit down with a blank page tonight and write out the two name tables from memory. Get one wrong? Write the whole table again. Do that three evenings in a row and this unit is finished for good, and you will walk into the paper having already banked marks that many of your classmates will lose by guessing. Start with the table, not with the reading. You can do this.

🧪 Chapter 1 · History of Chemistry