{"id":"silicon-atom","level":"matter","name":"Silicon atom","shortName":"Silicon","role":"Supplies the electronic states from which semiconductor behavior is engineered.","description":"Silicon begins the atlas at the scale of matter. A neutral atom has fourteen electrons, with four in its outer occupied shell. That electron structure matters because neighboring silicon atoms can share electrons in bonds, creating a solid with electronic behavior unlike either an isolated atom or a metal. The atlas represents the nucleus and electron probability regions schematically; electrons do not orbit on neat planetary tracks. An atom is also not a digital bit. Computation appears only after enormous numbers of atoms are arranged into materials, devices, circuits, and controlled signals. Follow the lattice connection to see the first collective structure in that chain.","specs":[{"label":"Atomic number","value":"14","context":"Number of protons; also electrons in a neutral atom."},{"label":"Outer-shell electrons","value":"4","context":"The 3s²3p² ground-state configuration."},{"label":"Representation","value":"Quantum-state schematic","context":"Displayed electron regions are explanatory, not trajectories."}],"interfaces":[{"name":"Neighboring atoms","direction":"in","signal":"Shared electronic states and chemical bonding"},{"name":"Crystal material","direction":"out","signal":"Collective solid-state behavior"}],"tradeoff":"Atomic properties constrain material choice. Fabrication must control defects and interfaces as well as the element itself.","whyAI":"An individual silicon atom performs no AI operation. Its collective electronic behavior makes controllable hardware possible.","related":["crystal-lattice","energy-bands"],"sources":[{"title":"NIST — Atomic Data for Silicon","url":"https://physics.nist.gov/PhysRefData/Handbook/Tables/silicontable1_a.htm"}],"scale":"Subnanometer; atom drawing is conceptual","kind":"atom","mechanism":["Identify the nucleus and the fourteen-electron structure of a neutral silicon atom.","Focus on the four outer-shell electrons that participate in bonding with neighbors.","Join many atoms to obtain collective material behavior, then continue to devices and circuits."],"misconception":"A silicon atom is not a miniature digital processor; computation requires organized devices, circuitry, and controlled signals.","check":{"question":"Where does a silicon atom become a digital bit?","options":["An isolated atom always stores one bit","Only through an engineered physical encoding in a larger device or circuit","Each outer electron is a permanent binary register"],"answer":1,"explanation":"Bits are information encodings. The atlas moves from atomic properties to a circuit that deliberately represents two states."},"branch":"Atomic foundations","subbranch":"Atomic states","science":[{"title":"Charge bookkeeping","equation":"Q = (Z − Nₑ)e","explanation":"Z counts protons and Nₑ counts electrons. Neutral silicon has Z = Nₑ = 14; gaining or losing electrons changes charge without changing the element.","assumptions":"Bookkeeping relation for an isolated atom or ion; it does not describe quantum orbital shapes."}],"history":[],"learningObjective":"Relate atomic charge and electron count to a material model.","engineeringExample":"Teaching check: a neutral silicon atom has equal proton and electron counts; ionization changes charge bookkeeping without changing the nucleus.","evidenceNotes":"Atomic notation is a model of composition, not a device-level mobility prediction.","visualFamily":"device-crosssection","prerequisites":[],"labId":"library","scope":"Use the switching investigation to connect physical charge, circuit load and arithmetic; the numerical library has no standalone model of this lesson’s full mechanism.","investigationId":"switching","labScope":"Use the switching investigation to connect physical charge, circuit load and arithmetic; the numerical library has no standalone model of this lesson’s full mechanism."}