Rock cycle and chem

Matter: Anything that has mass and takes up space. Atoms: The smallest unit of an element. Elements: Pure substances made of only one type of atom. Molecules: Two or more atoms bonded together. Compounds: Substances made from two or more different elements chemically joined. Mixtures: Two or more substances physically combined (not chemically). Representations: 2D models – formulas (e.g., H₂O, CO₂) 3D models – ball-and-stick or space-filling diagrams LG2 – Physical and Chemical Changes Physical Change: Changes in state or form; no new substance formed. Examples: melting, boiling, dissolving, crushing. Particles rearrange but stay the same type. Chemical Change: New substances are formed. Signs of chemical change: Colour change Gas produced (bubbling, fizzing) Temperature change (heat/light released or absorbed) Precipitate forms (solid appears) Indicators of energy change: exothermic (releases heat), endothermic (absorbs heat). Chemical Equations: Show reactants → products. Example: H₂ + O₂ → H₂O Differences between physical & chemical changes: Physical: reversible, no new substance. Chemical: irreversible, new substance formed. 🌍 Earth and Space Summary Notes LG1 – The Rock Cycle Three main rock types: Igneous – formed from cooling magma/lava. Extrusive: cools quickly on surface → small crystals (e.g., basalt). Intrusive: cools slowly underground → large crystals (e.g., granite). Sedimentary – formed from weathering, erosion, compaction & cementation of sediments. Often contains fossils. Metamorphic – formed from heat and pressure acting on existing rock (e.g., limestone → marble). Fossil evidence helps determine the relative age of sedimentary layers. Rock cycle: rocks change type through melting, cooling, weathering, and metamorphism. LG2 – Plate Tectonics Layers of the Earth: Crust – thin, solid outer layer. Mantle – thick, semi-solid rock layer with convection currents. Outer core – liquid iron and nickel. Inner core – solid iron and nickel. Continental Drift: Continents move slowly over time (evidence: matching fossils, rock formations, continental fit). Plate Tectonics Theory: Earth’s crust is divided into plates that move on the mantle. Plate Boundaries: Divergent – plates move apart (volcanoes, mid-ocean ridges). Convergent – plates move together (mountain ranges, subduction zones, volcanoes). Transform – plates slide past each other (earthquakes). Constructive vs Destructive: Constructive: creates new crust (divergent). Destructive: destroys old crust (convergent). Faults & Folds: Faults – cracks where rocks move. Folds – bending of rock layers due to pressure.