巨大共有結合構造：結合は固体全体を通じて継続する
導入済み| English | 意味 |
|---|---|
| silicon dioxide/ˈsɪlɪkən daɪˈɒksaɪd/ | 二酸化ケイ素 |
| giant covalent structure/ˈdʒaɪənt ˈkəʊvələnt ˈstrʌktʃə/ | 巨大共有結合構造 |
What would explain this observation?
- A drawing showing one silicon atom bonded to four oxygens is only a local piece of silica. The oxygen bridges continue into a network, so the pictured fragment is not a separate SiO₄ molecule.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Diamond, graphite and silicon dioxide 二氧化硅 have giant covalent structures 巨型共价结构. Strong covalent bonds join atoms through large repeating structures, rather than a substance made of small independent molecules. Many strong covalent bonds must be overcome to melt these structures, requiring much energy and producing very high melting points. They are solids under ordinary conditions.
- giant covalent structure: An extended network of atoms connected by strong covalent bonds; silicon dioxide: A substance with a giant covalent structure and overall silicon-to-oxygen ratio 1:2.
ケイ酸塩为何具有极高的熔点？
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ケイ酸石英中では、融解に際して巨大構造全体にわたる強い共有結合を切断する必要がある。別々の SiO2 分子が存在せず、容易に離れることができない。この強い結合ネットワークが融点が高い理由である。
各専門用語を正確な意味と対応させよ。
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関連する物理量やプロセスを区別するために定義を使用せよ。
Choose evidence that can test it
- In silicon dioxide, each silicon is linked to four oxygens and each oxygen bridges two silicons, producing the overall Si:O ratio 1:2. A local drawing may show four surrounding oxygens because each is shared with another silicon elsewhere in the network. Graphite has strongly bonded layers but weaker attractions between layers; its high-temperature behaviour and layer sliding concern different connections.
- Trace bonds from one atom to its neighbours and then onward beyond the fragment. Distinguish an uninterrupted network from separate groups with gaps between them. Compare a local coordination drawing and the bulk formula. Models may omit remote bonds, distort angles or enlarge spaces; explain what the representation does and does not establish.
この場合、調査やモデルをより妥当にする2つの習慣は何か。
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条件や仮定を明記することで他者が正確に再現でき、根拠となる証拠を記録することで結論を検証できます。相反する結果を隠すと、誤った結論を疑う証拠を失いますし、単一の測定でより広い主張を成立させることはできません。
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a stated representative silica region contains twelve silicon atoms and twenty-four oxygen atoms. The ratio 12:24 reduces to 1:2, giving SiO₂. It is a ratio in a continuing structure, not proof of twelve independent SiO₂ molecules. A local four-oxygen coordination shell cannot be counted without the sharing information to infer the bulk formula.
A representative silica region contains 18 silicon atoms. At the Si:O ratio 1:2, how many oxygen atoms does it contain? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
代表的なケイ酸領域に 18 個のケイ素原子が含まれています。Si:O 比が 1:2 の場合、この領域に含まれる酸素原子はいくつありますか？
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結果は 36 個の原子である。既知: 18 個のケイ素原子; Si:O 比 1:2。酸素原子数 = 18 × 2 = 36 個。この比は連続的な構造を表しており、 discrete molecules（個別の分子）ではない。
Check the conclusion and its limits
- Giant structure does not mean giant individual atoms. Melting a covalent network differs from boiling a small molecular substance because the relevant connections differ. Not all giant covalent substances are electrical insulators: graphite is a key exception with delocalised electrons.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
The four oxygens around one silicon mean the bulk silica formula must be SiO₄. This claim is false: Each oxygen in the network is SHARED between two silicon atoms, so four around one silicon contribute only half each: 4 x 1/2 = 2, giving SiO2. Counting without sharing double-counts the oxygens.
Giant covalent structures: connections continue through the solid: In silicon dioxide, each silicon is linked to four oxygens and each oxygen bridges two silicons, producing the overall Si:O ratio 1:2. A local drawing may show four surrounding oxygens because each is shared with another silicon elsewhere in the network. Graphite has strongly bonded layers but weaker attractions between layers; its high-temperature behaviour and layer sliding concern different connections.
1つのケイ素を取り囲む4つの酸素は、全体化学式がSiO₄でなければならないことを意味する。
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ネットワーク中の各酸素原子は2つのケイ素原子間で共有されるため、1つのケイ素を取り囲む4つはそれぞれ半分ずつ寄与する: 4 × 1/2 = 2 となり、SiO2 が得られる。共有を考慮せずに数えると酸素が二重にカウントされる。
強い共有結合によって結ばれた原子の拡張ネットワーク：技術用語を記せ。
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giant covalent structureとは、強い共有結合によって結ばれた原子の拡張ネットワークを指す。