Spain 4º ESO Physics and Chemistry

Chapters: 5

1. Basic scientific skills

Experimental work and projects · Science learning environments · Lab and safety rules · Scientific language and units · Interpreting scientific information · Scientific culture and scientists

Research Skills: From a Question to a Finished Project – Research is a careful way of finding an answer. You ask a clear, focused question, plan how to answer it, find information and check that each source can be trusted, collect and analyse your own data, draw a conclusion that the evidence supports, and share it while crediting every source you used.
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.
Units and Measurement (Class 11) – To measure means to compare a quantity with a fixed, agreed amount called a unit. Result = number × unit. The world now uses the SI system with 7 base units: metre, kilogram, second, ampere, kelvin, mole and candela. Every other unit (like newton or joule) is a derived unit made by multiplying or dividing base units. Prefixes like kilo (10³) and milli (10⁻³) make very big or very small numbers easy.
Media Literacy – Media literacy is the skill of reading, questioning and creating media: news, ads, videos, posts, films and games. Every media text is made by someone, for a purpose, for an audience, using forms, conventions and techniques that shape how we feel. A media-literate person checks the source, evidence, other coverage and the original before believing or sharing, notices bias and filter bubbles, and makes their own media responsibly.
History of Science: How Our Ideas About Nature Changed – Science grew slowly over 5,000 years. Early civilisations watched the sky to make calendars. Greek thinkers asked why things happen and used reason. Indian and Islamic scholars gave us zero, algebra and careful experiments. In the Scientific Revolution, Copernicus, Galileo and Newton replaced the Earth-centred model with a Sun-centred one and tested ideas by experiment. Modern science brought atoms, evolution, relativity and quantum theory. Each step shows the same lesson: good evidence can overturn old ideas.

2. Matter

Solutions and gases · Atomic models · Electron configuration · Chemical compounds and uses · The mole · Inorganic nomenclature · Introduction to organic nomenclature

Solutions: How Things Dissolve and How Much Can Dissolve – A solution is a uniform mixture of a solute dissolved in a solvent. In water (an aqueous solution) the solute breaks into particles too small to see, so it never settles and passes through filter paper. Concentration tells how much solute is present (mass % = solute ÷ solution × 100). Solubility is the most that can dissolve in 100 g of solvent at a given temperature; beyond it the solution is saturated. Evaporation, crystallisation and distillation separate solutions.
Structure of the Atom – An atom has a tiny, heavy, positive nucleus made of protons and neutrons. Electrons move around it in fixed shells K, L, M, N. The number of protons (Z) tells the element; protons + neutrons give the mass number (A). Outer electrons decide valency. Isotopes share Z; isobars share A.
Electronic Configuration and the s, p, d, f Blocks – The periodic table is really a map of electron filling. The period number is the highest shell (n) being used. The block is the subshell that receives the last electron: s-block (groups 1–2, ns¹⁻²), p-block (groups 13–18, ns² np¹⁻⁶), d-block (groups 3–12, (n−1)d¹⁻¹⁰ ns⁰⁻²) and f-block (lanthanoids and actinoids, (n−2)f¹⁻¹⁴ (n−1)d⁰⁻¹ ns²). Group: s-block = number of ns electrons; p-block = 10 + ns + np electrons; d-block = ns + (n−1)d electrons.
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.
Mole Concept, Molar Mass and Chemical Formulas – Atoms are far too small to count one by one, so chemists count them by weighing. Atomic masses are given in u, where 1 u is one-twelfth the mass of a carbon-12 atom. One mole is 6.022 × 10²³ particles, and its mass in grams equals the formula mass in u. With moles we can find the percentage of each element in a compound, and work back from percentages to the empirical and molecular formulas.
IUPAC Nomenclature and Isomerism of Organic Compounds – Millions of organic compounds exist, so every one needs a clear, unique name. The IUPAC system builds a name from three parts: the word root (number of carbons in the main chain), the suffix (type of bond and main functional group) and the prefixes (side groups). You pick the longest chain that holds the main group, number it so the main group and branches get the lowest numbers, and write side groups in alphabetical order. Isomers are compounds with the same molecular formula but different arrangement. Structural isomers differ in how atoms are joined (chain, position, functional group, metamerism). Stereoisomers are joined the same way but differ in 3D arrangement (geometrical cis/trans and optical isomers).
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.

3. Energy

Mechanical energy and conservation · Energy transfer: work and heat · Energy in our world

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.
Minerals and Energy Resources – Minerals are natural substances found in rocks. They are metallic (ferrous or non-ferrous), non-metallic, or energy minerals. Energy comes from conventional sources like coal, petroleum, natural gas and electricity, and from non-conventional sources like sun, wind, nuclear, biogas, tides and heat from the Earth. Both minerals and energy must be conserved.

4. Interaction

Describing motion · Force as agent of change · Forces as vectors · Everyday forces · Universal gravitation · Forces and pressure in fluids

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.
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.
Forces: Pushes and Pulls – A force is a push or a pull between two objects. It is measured in newtons (N). Contact forces need touching (push, friction, normal force, tension, buoyancy); non-contact forces act at a distance (gravity, magnetism, electric). A force is drawn as an arrow: start = point of application, direction, length = size. Forces can change an object's speed, direction or shape. If forces balance, a still object stays still (equilibrium). Forces always come in pairs: if A pushes B, B pushes A back equally (Newton's third law).
Newton's Universal Law of Gravitation – Every mass in the universe pulls every other mass. The pull between two point masses m₁ and m₂ a distance r apart is F = G m₁ m₂ / r². It acts along the line joining them. The two bodies pull each other with equal and opposite forces. G = 6.67 × 10⁻¹¹ N m² kg⁻² is the same everywhere, so it is called the universal gravitational constant. When many masses pull one body, the forces add as vectors (superposition).
Pressure in Fluids and Pascal's Law – A fluid (liquid or gas) pushes on every surface it touches. Pressure is this normal force per area, P = F/A. Because of gravity, the fluid above a point has weight, so pressure grows with depth: P = P₀ + ρgh. Points at the same depth in a still liquid have the same pressure, whatever the vessel's shape. Pascal's law says an extra pressure applied to an enclosed fluid reaches every point equally. The hydraulic lift and brakes use this: a small force on a small piston becomes a big force on a big piston, F = f × A/a.

5. Change

Chemical equations and stoichiometry · Important chemical reactions · Reaction rate factors

Stoichiometry, Limiting Reagent and Concentration Terms – Stoichiometry means measuring the amounts of substances in a reaction. A balanced equation acts like a recipe: its numbers give the mole ratio of reactants and products. With it you can change any mass into moles, use the ratio, and change back to the mass of any other substance. The reactant that runs out first is the limiting reagent; it decides how much product forms. For solutions, concentration is given as mass percent, mole fraction, molarity or molality.
Chemical Reactions and Balancing Equations – In a chemical reaction atoms are not made or destroyed; they only change partners. So a chemical equation must have the same number of each kind of atom on both sides. We balance it by changing the numbers in front of formulas, never the formulas themselves.
Rates of Reaction – The rate of a reaction is how fast reactants are used up or products are made. Rate = change in amount ÷ time. Particles must collide with at least the activation energy to react. More frequent, more energetic collisions mean a faster rate. Raising concentration (or gas pressure), temperature or surface area, or adding a catalyst, makes reactions faster. A catalyst gives a path with lower activation energy and is not used up.