France Première STL (laboratory sciences) — 1re specialties
Chapters: 9
1. Physics-chemistry: Constitution of matter
Structure and properties of chemical species · Solvents and solutes
- Chemical Bonding: Ionic, Covalent and Metallic Bonds – Atoms join together (bond) to become more stable. Only their outer electrons take part. Most atoms are most stable with 8 outer electrons: the octet rule. There are three main ways to reach it. In an ionic bond, a metal gives electrons to a non-metal, making oppositely charged ions that attract. In a covalent bond, two non-metals share pairs of electrons to make molecules. In a metallic bond, metal atoms release outer electrons into a shared 'sea' that holds positive ions together. The difference in electronegativity (how strongly an atom pulls shared electrons) tells us which kind of bond forms. The type of bond explains melting points, whether a substance conducts electricity, and whether it dissolves in water.
- Kossel-Lewis Approach and the Ionic Bond – Atoms join so that each gets a stable outer shell of 8 electrons (an octet), like a noble gas. Kossel said atoms can give or take electrons to make ions (ionic bond). Lewis said atoms can also share pairs of electrons (covalent bond). Lewis structures show these electrons as dots and lines. Formal charge (V − L − B/2) helps pick the best Lewis structure. Ions pack into a crystal, and the energy released is linked to the lattice enthalpy.
- Solutions: Types, Concentration and Henry's Law – A solution is an even mix of two or more substances. The part in bigger amount is the solvent, the smaller part is the solute. We tell 'how strong' a solution is with concentration terms: mass %, volume %, ppm, mole fraction, molarity (per litre of solution) and molality (per kg of solvent). Solids usually dissolve more when hot. Gases dissolve more when their pressure is high (Henry's law, p = KH·x) and less when it is hot.
2. Physics-chemistry: Chemical transformation
Acid–base reactions in water · Reaction kinetics
- Acids and Bases: Properties, Indicators and Reactions – An acid gives H⁺ ions in water and a base gives OH⁻ ions. Indicators show which one is present by a colour or smell change, and when H⁺ meets OH⁻ they make water, leaving a salt behind.
- Rate of a Chemical Reaction – The rate of a reaction tells how fast a reactant is used up or a product is made, per unit time. Rate = −Δ[R]/Δt = +Δ[P]/Δt (unit mol L⁻¹ s⁻¹). The rate law, rate = k[A]^x[B]^y, is found by experiment; x + y is the order. Molecularity is the number of particles that collide in one elementary step.
3. Physics-chemistry: Motion and interactions
Motion · Interactions · Energy aspects
- Motion: Distance, Speed, Velocity, Acceleration and Graphs – An object is in motion when its position changes with time. Distance is the full path length (a scalar); displacement is the straight gap from start to finish with a direction (a vector). Speed = distance ÷ time; velocity = displacement ÷ time. Acceleration = change in velocity ÷ time. The slope of an s–t graph gives velocity, the slope of a v–t graph gives acceleration, and the area under a v–t graph gives the distance. For uniform acceleration: v = u + at, s = ut + ½at², v² = u² + 2as.
- Force and Laws of Motion – A force is a push or a pull. Balanced forces (net force zero) do not change motion; an unbalanced force changes speed or direction. Friction opposes sliding. First law: a body keeps its state of rest or uniform motion unless an unbalanced force acts (inertia; heavier bodies have more inertia). Momentum p = mv. Second law: F = ma (rate of change of momentum), 1 N = 1 kg m/s². Third law: forces come in equal and opposite pairs acting on two different bodies. For a system with no outside force, internal forces cancel and total momentum is conserved.
- Work, Energy and Power – Work is done when a force moves an object: W = F × s, measured in joules (J). Energy is the ability to do work. A moving body has kinetic energy ½mv²; a raised body has potential energy mgh. Energy is never made or destroyed, only changed from one form to another. Power is how fast work is done: P = W ÷ t, in watts. Simple machines like levers and pulleys let a small effort move a big load.
4. Physics-chemistry: Waves and signals
Mechanical waves · Electromagnetic waves
- Sound – Sound is made by vibrating objects. It travels through a medium (air, water, solids) as a longitudinal wave: particles move back and forth, making crowded parts (compressions) and spread-out parts (rarefactions). Frequency (Hz) sets the pitch, amplitude sets the loudness, and speed v = f × λ. Sound cannot travel in vacuum. Humans hear 20 Hz to 20,000 Hz; below is infrasound, above is ultrasound. Reflected sound gives echoes, used and controlled in buildings.
- Electromagnetic Waves – A changing electric field acts like a current, called the displacement current, and it makes a magnetic field. A changing magnetic field makes an electric field. Together they travel as an electromagnetic (EM) wave at c = 3 × 10⁸ m/s, even through empty space. E and B are at right angles to each other and to the direction of travel, so EM waves are transverse. Sorted by wavelength, they form the spectrum: radio, microwave, infrared, visible, ultraviolet, X-rays and gamma rays.
5. Mathematics
Trigonometry · Dot product · Derivatives · Antiderivatives
- Trigonometric Functions: Radians, Unit Circle, Graphs and Identities – An angle of one radian cuts an arc equal to the radius, so π radians = 180°. On a unit circle, the point at angle x is P = (cos x, sin x), which gives sin²x + cos²x = 1 and extends sine and cosine to every real number. The signs follow 'All, Sin, Tan, Cos' in quadrants I to IV; sin x and cos x repeat every 2π and stay between −1 and 1. Compound-angle formulas such as cos(A + B) = cos A cos B − sin A sin B lead to tan(A + B), cot(A + B), sum-to-product, double-angle and triple-angle identities.
- Vector Algebra – A vector has a size (magnitude) and a direction. In 3D we write it as a = xî + yĵ + zk̂. Its length is |a| = √(x² + y² + z²). Its direction cosines are l = x/|a|, m = y/|a|, n = z/|a|, and l² + m² + n² = 1. Vectors are added head-to-tail (triangle law) or component by component. ka stretches a by k and flips it if k is negative. The point dividing AB in m : n has position vector (mb + na)/(m + n) inside and (mb − na)/(m − n) outside. Dot product a·b = |a||b|cosθ gives a number and tells the angle and the projection. Cross product a×b = |a||b|sinθ n̂ gives a vector at right angles to both; its length is the area of the parallelogram on a and b.
- Continuity and Differentiability – A function is continuous at a point when its graph has no break there: the left limit, the right limit and the value are all equal. The derivative is the slope of the tangent line. With the chain rule, implicit differentiation, the rules for eˣ, ln x and inverse trig functions, logarithmic differentiation and parametric forms, you can differentiate almost any Class 12 function. The second derivative tells how the slope itself changes, that is, how the curve bends.
- Integrals – Integration undoes differentiation: if F′(x) = f(x), then ∫f(x) dx = F(x) + C. We integrate with standard formulas, substitution (replace an inside part by u), partial fractions (split a fraction) and by parts (∫u dv = uv − ∫v du). A definite integral ∫ₐᵇ f(x) dx is the signed area under the curve from a to b, and the fundamental theorem says it equals F(b) − F(a). Its properties make many hard integrals easy.
6. Biochemistry-biology: thematic modules
Digestion · Excretion · Reproductive physiology · Molecular genetics
- Human Digestive System and Heterotrophic Nutrition – Heterotrophs take ready-made food from other living things. Humans are holozoic: we eat whole food and break it down in a long tube, the alimentary canal. Teeth, saliva, stomach acid, enzymes, bile and pancreatic juice cut big food molecules into small ones that villi in the small intestine absorb into blood.
- Excretory Products and their Elimination – Animals must remove nitrogen waste. Ammonia is most toxic and needs lots of water; urea is less toxic; uric acid needs least water. Humans are ureotelic. Each kidney has about a million nephrons. Urine forms in three steps: glomerular filtration (about 125 mL/min, 180 L/day), reabsorption (about 99% taken back) and secretion. The loop of Henle and vasa recta make the medulla salty by a counter-current mechanism, so urine can be concentrated. ADH, the renin-angiotensin-aldosterone system and ANF control water and salt. Lungs, liver, skin and sweat also help. Failed kidneys need dialysis or a transplant.
- Reproduction in Human Beings and Reproductive Health – At puberty, hormones from the brain make the testes and ovaries start working. The male system makes and carries sperm; the female system makes eggs and provides a place (uterus) where a baby develops. Fertilisation happens in the oviduct, and the embryo is fed through the placenta. Reproductive health includes safe choices, contraception, avoiding female foeticide, and preventing sexually transmitted diseases such as HIV/AIDS.
- Heredity and Mendel's Laws – Heredity is the passing of traits from parents to children through genes. Each parent gives one copy of every gene. A dominant copy hides a recessive one, which is why Mendel saw 3:1 in a monohybrid cross and 9:3:3:1 in a dihybrid cross. Genes are pieces of DNA that make proteins, and proteins build the trait.
7. Biochemistry-biology: cross-cutting modules
Structure and properties of biomolecules · Structure and physiological function · Internal environment and homeostasis · Information and communication
- Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
- The Cell: Basic Unit of Life – Every living thing is made of cells. Robert Hooke first saw cells in cork in 1665. Cells are prokaryotic (no true nucleus, like bacteria) or eukaryotic (true nucleus). Plant cells have a cell wall, chloroplasts and a big vacuole; animal cells do not. Each organelle has a job. Water enters and leaves cells by osmosis. Cells make new cells by mitosis (growth) and meiosis (sex cells).
- Homeostasis – Homeostasis is how the body keeps its internal environment (blood and tissue fluid) steady even when the outside world changes. It controls body temperature (about 37 °C), blood glucose (about 4–6 mmol/L), water and salt, and blood pH (about 7.4). It mostly uses negative feedback: a receptor senses a change, a control centre decides, and an effector brings the level back to its set point.
- Protein Synthesis: From Gene to Protein – A gene is a stretch of DNA that holds the recipe for one protein. In transcription, the cell copies the gene into messenger RNA (mRNA) inside the nucleus; U replaces T. The mRNA goes to a ribosome in the cytoplasm. In translation, the ribosome reads the mRNA three bases at a time (a codon). Each codon matches one amino acid, carried in by a transfer RNA (tRNA). The amino acids join into a chain that folds into a protein. A change in the DNA (a mutation) can change the protein.
8. Biotechnology (option)
Experimental research and project work · Lab risk prevention · Reliable measurements · Digital tools in biotechnology · Observing microscopic life · Culturing microorganisms · Identifying microorganisms · Counting microorganisms · Preparing lab solutions · Detecting biomolecules · Separating mixtures · Measuring biomolecule concentration
- Lab Skills: How to Do a Good Experiment – A good experiment starts with a clear question that can be tested. You plan a fair test: change one thing (the independent variable), measure one thing (the dependent variable) and keep all the others the same (controlled variables). You measure with the right instrument, repeat the measurement, and take the mean. The spread of the readings, half the range, tells you the uncertainty. You write everything in a lab notebook (date, aim, method, table, observations) and then in a report (aim, method, results, graph, conclusion, evaluation). The same skills help in lab projects and in everyday science, like testing which detergent works best.
- Lab Safety and Safe Experiments – Dress for safety (goggles, coat, closed shoes, hair tied). Read labels and hazard pictograms. Heat gently with the mouth of the tube pointing away. Add acid to water, waft smells, never taste. Report every accident at once. Plan experiments step by step, assess the risks first and dispose of waste correctly.
- Matter and Its Measurement – Matter is anything that has mass and takes up space. It can be solid, liquid or gas, and it can be an element, a compound or a mixture. Chemists measure matter in SI units. Every measurement has some doubt, so we write it with the right number of significant figures, use scientific notation for very big or small numbers, and change units with conversion factors.
- Bioinformatics: Computers in Biology – Bioinformatics uses computers to store, search and compare biological data. Lab results go into spreadsheets; DNA and protein sequences go into online databases; alignment tools compare sequences to find matches, differences (like SNPs) and relatives; image software measures what a microscope camera sees. Data about people must be kept private and used fairly.
- Microorganisms: The Tiny Living Things All Around Us – Microorganisms (microbes) are living things too small to see without a microscope. The main groups are bacteria, fungi, protozoa and algae; viruses are also studied with them but are not cells. Bacteria have no nucleus (prokaryotes); the others have one (eukaryotes). Bacteria multiply by splitting in two, so their number doubles again and again. Most microbes are harmless or helpful: our gut microbiota helps digestion, microbes make curd and bread, recycle dead matter and fix nitrogen. A few are pathogens that cause disease. Antibiotics kill bacteria but not viruses, and misusing them breeds resistant bacteria.
- Microbiology: How to Grow, Identify and Count Microbes – In a microbiology lab we grow microbes on agar, choose the one we want with a selective medium, test drugs on them (antibiogram), identify them by shape, Gram stain and metabolic tests, and count them by microscope or by plate count (CFU/mL = colonies × dilution factor ÷ volume plated).
- Solutions: Types, Concentration and Henry's Law – A solution is an even mix of two or more substances. The part in bigger amount is the solvent, the smaller part is the solute. We tell 'how strong' a solution is with concentration terms: mass %, volume %, ppm, mole fraction, molarity (per litre of solution) and molality (per kg of solvent). Solids usually dissolve more when hot. Gases dissolve more when their pressure is high (Henry's law, p = KH·x) and less when it is hot.
- Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
- Purification and Analysis of Organic Compounds – A compound made in a lab or taken from a plant is never pure at first. We purify it by using a difference in properties: solubility (crystallisation), boiling point (distillation and its types), sublimation, solubility in two liquids (differential extraction) or how strongly it sticks to a surface (chromatography). A pure solid has a sharp melting point. Next we find which elements are present (qualitative analysis): carbon and hydrogen by heating with copper(II) oxide, and N, S, halogens and P by Lassaigne's sodium fusion test. Finally we find how much of each element is present (quantitative analysis): Liebig's method for C and H, Dumas and Kjeldahl methods for N, Carius method for halogens and S, and oxygen by difference. From the percentages we can get the empirical formula.
- Spectroscopy and the Beer-Lambert Law – Spectroscopy studies how matter absorbs or gives out light. Light is made of photons with energy E = hf = hc/λ. Atoms give line spectra because electrons jump between fixed energy levels. A coloured solution absorbs its complementary colour. A spectrophotometer measures transmittance T = I/I₀ and absorbance A = log₁₀(I₀/I). The Beer-Lambert law says A = εlc, so a calibration line of A against c lets us find an unknown concentration.
9. Lab physical and chemical sciences (option)
Measurement and uncertainty · Chemistry: safety and environment · Chemistry: organic synthesis · Chemistry: physico-chemical analysis · Image: colour and vision · Image: photography and digital camera · Image: storing and sending digital images · Instrumentation · Project linked to research or industry
- Matter and Its Measurement – Matter is anything that has mass and takes up space. It can be solid, liquid or gas, and it can be an element, a compound or a mixture. Chemists measure matter in SI units. Every measurement has some doubt, so we write it with the right number of significant figures, use scientific notation for very big or small numbers, and change units with conversion factors.
- Lab Safety and Safe Experiments – Dress for safety (goggles, coat, closed shoes, hair tied). Read labels and hazard pictograms. Heat gently with the mouth of the tube pointing away. Add acid to water, waft smells, never taste. Report every accident at once. Plan experiments step by step, assess the risks first and dispose of waste correctly.
- Carbon and Its Compounds: Bonding, Hydrocarbons and Naming – Carbon has 4 outer electrons, so it shares electrons (covalent bonds) instead of gaining or losing them. Because it bonds to itself (catenation) and always makes 4 bonds (tetravalency), it forms millions of compounds: chains, branches and rings, saturated or unsaturated. Compounds with the same functional group form a homologous series that differs by –CH₂–, and IUPAC names are built from the number of carbons + a suffix or prefix for the functional group.
- Spectroscopy and the Beer-Lambert Law – Spectroscopy studies how matter absorbs or gives out light. Light is made of photons with energy E = hf = hc/λ. Atoms give line spectra because electrons jump between fixed energy levels. A coloured solution absorbs its complementary colour. A spectrophotometer measures transmittance T = I/I₀ and absorbance A = log₁₀(I₀/I). The Beer-Lambert law says A = εlc, so a calibration line of A against c lets us find an unknown concentration.
- Light and Colour: Mixing, Seeing and Energy of Light – White light is a mix of colours (red to violet). Lights add: red + green + blue make white (additive mixing, used by screens). Paints take away: cyan + magenta + yellow make near-black (subtractive mixing). An object has a colour because it reflects some colours and absorbs the rest. Eyes use three kinds of cone cells. Light colour tells its energy: E = hf, blue photons carry more energy than red.
- Spherical Lenses: Images, Lens Formula and Power – A convex lens is thick in the middle and bends parallel light to meet at its focus; a concave lens is thin in the middle and spreads light out as if from its focus. With two simple rays (one parallel to the axis, one through the optical centre) you can find the image for any object position. A convex lens gives real, inverted images when the object is beyond F₁ and a virtual, erect, enlarged image inside F₁; a concave lens always gives a virtual, erect, diminished image. The lens formula 1/v − 1/u = 1/f, magnification m = v/u and power P = 1/f (in metres, unit dioptre) let you solve lens numericals.
- Digital Media: How Pictures, Sound and Video Become Numbers – Digital media is any picture, sound, video or animation stored as numbers on a computer. A raster image is a grid of pixels, each stored as red, green and blue values from 0 to 255. Vector graphics store shapes as maths, so they stay sharp at any size. Video and animation are many frames shown quickly. File size grows with resolution and colour depth, so we use compression. When we make or share media we must respect copyright, licences and people's image rights, and work safely and critically.
- Sensors: How Machines Sense the World – A sensor turns a physical quantity (light, temperature, distance, moisture, sound, pressure) into an electrical signal. Analogue sensors give a smooth voltage; an ADC turns it into a number the computer can use. A controller compares the number with a threshold and switches an actuator, often through a relay. Readings taken at regular times are data logging. Good sensors have the right range, sensitivity, accuracy and response time.
- Project Management – A project is a one-time piece of work with a clear goal, a start and an end. Project management means planning and controlling it so it meets its scope on time and within cost. The life cycle runs initiate, plan, execute, monitor and close. Planners break the work into tasks (WBS), place them on a Gantt chart, find the critical path, manage risks and review lessons learned at the end.