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Physics-Chemistry Seconde revision sheet: atoms, periodic table, mole, chemical reactions, motion, forces, waves, light. Full French program 2026.
The Seconde physics-chemistry curriculum builds the scientific foundations for further studies. It covers three main themes: Matter, Motion and Interactions, and Waves and Signals, plus a section on The Universe.
The atom consists of a dense nucleus (protons and neutrons) surrounded by electrons. Atomic number Z = number of protons. Mass number A = protons + neutrons. Isotopes share the same Z but differ in A (e.g., ¹²C, ¹³C, ¹⁴C).
Electrons fill shells K (max 2), L (max 8), M (max 8 at this level). Elements in the same column share the same number of valence electrons and belong to the same chemical family: alkali metals (column 1, 1 valence electron), halogens (column 17, 7), noble gases (column 18, full outer shell).
Atoms bond to achieve a stable configuration (duet rule for H/He, octet rule for others). Covalent bonds involve shared electron pairs. Lewis structures show bonding and lone pairs. Ions form when atoms gain (anions, e.g., Cl⁻) or lose electrons (cations, e.g., Na⁺).
The mole contains N_A = 6.022×10²³ entities. Molar mass M (g·mol⁻¹): M(H₂O) = 18.0. Amount: n = m/M. Molar concentration: C = n/V. Dilution conserves solute amount: C₀V₀ = C₁V₁.
Reactions convert reactants into products. Equations must be balanced (element and charge conservation). Stoichiometry gives molar ratios. The limiting reactant is consumed first and determines maximum advancement. An advancement table tracks amounts as a function of x.
Motion is relative to a frame of reference. Trajectory: set of successive positions. Average speed: v = d/Δt (m·s⁻¹). Types: uniform (constant speed), accelerated (increasing speed), decelerated (decreasing speed).
In a Galilean frame, if forces on an object are balanced (net force = 0), the object remains at rest or in uniform rectilinear motion. If forces are unbalanced, the motion changes.
Weight: P = mg (g ≈ 9.81 N·kg⁻¹). Gravitational force: F = Gm₁m₂/d² (G = 6.674×10⁻¹¹ N·m²·kg⁻²). Normal reaction: perpendicular contact force from a surface. Forces are represented by vectors with a point of application, direction, sense, and magnitude.
A mechanical wave needing a medium. Frequency f (Hz) determines pitch. Period T = 1/f. Human hearing: 20–20,000 Hz. Speed in air: ~340 m·s⁻¹; in water ~1,500 m·s⁻¹. Sound level in dB: 85 dB = danger threshold for prolonged exposure, 120 dB = pain threshold.
Travels in straight lines in homogeneous media. Speed in vacuum: c = 3.00×10⁸ m·s⁻¹. Refraction: Snell's law n₁sin(θ₁) = n₂sin(θ₂). Indices: air ≈ 1.00, water ≈ 1.33, glass ≈ 1.5. Visible spectrum: 400 nm (violet) to 800 nm (red). White light disperses through a prism into a continuous spectrum. Relation: λ = c/f.
Orders of magnitude from atomic nucleus (~10⁻¹⁵ m) to the observable universe (~9.3×10¹⁰ light-years). Light-year: distance light travels in one year ≈ 9.461×10¹⁵ m. Astronomical unit (AU): Earth–Sun distance ≈ 1.496×10¹¹ m. Structure: planets → solar system → galaxy (Milky Way, ~200 billion stars) → galaxy clusters → observable universe.