{"id": "card_chem_periodic_table", "kind": "reference", "title": "The periodic table — electrons in quantum shells", "body": "The elements are ordered by how electrons fill quantum shells (shell n holds 2n^2, sealed) under the Pauli exclusion principle. Helium closes 2, neon closes 8 (the octet), the third shell opens 18 (the transition metals). Many elements, one filling rule. Rests on quantum mechanics.", "source": {"label": "Narrow Highway — chemistry", "url": "", "authority_tier": "engine_derived"}, "shelf": "codex", "box": "chemistry", "bands": ["chemistry", "pillar", "periodic_table", "one map"], "subject": "The periodic table — electrons in quantum shells", "connections": [{"to_card_id": "card_floor_chemistry", "relationship": "part_of", "evidence": "a pillar of chemistry (The periodic table)"}, {"to_card_id": "card_floor_quantum_mechanics", "relationship": "connects_at", "evidence": "the periodic table is the Schrodinger equation plus Pauli exclusion: 2n^2 per shell"}], "author": "engine", "created_at": 0.0, "updated_at": 0.0, "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "generated": false, "call": "codex.chemistry", "facets": {"subject": ["one map", "periodic_table", "pillar"]}, "presentation": {"glyph": "•", "kind_label": "chemistry", "by": "Narrow Highway — chemistry", "authority": "engine_derived", "posted": "", "standing": ""}, "neighbors": [{"id": "card_floor_chemistry", "title": "Chemistry — quantum mechanics applied, the periodic table", "relationship": "part of", "why": "a pillar of chemistry (The periodic table)", "href": "/card/card_floor_chemistry", "resolved": true}, {"id": "card_floor_quantum_mechanics", "title": "Quantum mechanics — the quantum and its limits", "relationship": "connects at", "why": "the periodic table is the Schrodinger equation plus Pauli exclusion: 2n^2 per shell", "href": "/card/card_floor_quantum_mechanics", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_chem_periodic_table", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_chem_periodic_table"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}