混凝土凝固时为什么会收缩开裂，这和水分迁移有什么关系？
Why does setting concrete shrink and crack, and what role does water movement play?
混凝土凝固（水化）时，水泥与水反应生成凝胶并消耗水分；表面蒸发和内部水分向表面迁移（干燥收缩）使体积缩小，而内部约束限制了自由收缩，于是在内部产生拉应力。当拉应力超过混凝土早期抗拉强度时便开裂。控制水灰比、养护保湿、添加减缩剂或配筋可减轻收缩开裂。
As concrete sets, cement reacts with water (hydration) to form a gel and consumes water; evaporation from the surface and water migrating outward (drying shrinkage) make the volume shrink, but internal constraints prevent free contraction, building tensile stress. When that stress exceeds the young concrete's tensile strength, cracks form. Keeping the mix wet during curing, lowering the water–cement ratio, adding shrinkage reducers, or using reinforcement all help limit cracking.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#混凝土 #收缩 #水化
钙钛矿太阳能电池为什么效率飙升却快又脆？
Why are perovskite solar cells efficient yet fragile?
ABX₃ 钙钛矿光吸收强、载流子扩散长，所以效率迅速提高；但它遇水、热、光易降解，稳定性是产业化最大瓶颈。
ABX₃ perovskites absorb strongly and have long carrier diffusion, giving rapid efficiency gains; yet they degrade with water, heat and light, so stability is the key barrier.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#钙钛矿 #太阳能电池 #稳定性
为什么钯能像海绵一样吸氢气？
Why can palladium soak up hydrogen like a sponge?
钯可吸收相当于自身体积数百倍的氢气，氢以原子形式溶入钯晶格，这一性质用于氢气纯化和储存。
Palladium absorbs hundreds of times its volume in hydrogen, with H atoms dissolving into its lattice—used for hydrogen purification and storage.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#钯 #储氢 #吸附
钙钛矿太阳能电池为什么怕水和氧？
Why are perovskite solar cells vulnerable to water and oxygen?
钙钛矿材料遇湿气和氧气容易发生离子迁移与分解，导致效率快速衰减，因此封装是最大难题。
Perovskites suffer ion migration and decomposition when exposed to moisture and oxygen, so their efficiency fades fast—making encapsulation the big challenge.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#钙钛矿 #降解 #封装
为什么高温超导材料（如钇钡铜氧）只需液氮冷却就能超导？零电阻意味着什么？
Why does a high-temperature superconductor like YBCO superconduct with just liquid-nitrogen cooling, and what does zero resistance mean?
常规超导体（如铅、铌）的超导转变温度很低，只有几开尔文到20开尔文左右，必须用昂贵的液氦冷却。1986年科学家发现铜氧化物超导体后，很快研制出钇钡铜氧（YBa2Cu3O7，转变温度约92开尔文），超过液氮沸点77开尔文，只需廉价的液氮即可。零电阻意味着电流通过时不产生焦耳热、没有能量损耗，可以承载巨大的电流密度；超导体还完全排斥磁场（迈斯纳效应），从而实现磁悬浮。至今铜氧化物高温超导的机理仍在争论中，但零损耗输电和超导磁体已经开始改变技术面貌。
Conventional superconductors like lead and niobium have very low transition temperatures, only a few kelvin to about 20 K, and need expensive liquid helium. After copper-oxide superconductors were discovered in 1986, YBCO (YBa2Cu3O7, transition temperature about 92 K) quickly followed, exceeding the 77 K boiling point of liquid nitrogen, so it needs only cheap liquid nitrogen. Zero resistance means no Joule heating and no energy loss as current flows, so wires can carry enormous current densities; a superconductor also expels magnetic fields completely (the Meissner effect), enabling levitation. The mechanism of high-temperature superconductivity is still debated, yet lossless power lines and superconducting magnets are already reshaping technology.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#超导 #液氮 #钇钡铜氧
为什么合金（如钢）通常比组成它的纯金属更硬、更强？
Why are alloys such as steel usually harder and stronger than the pure metals they are made from?
金属受力变形主要靠晶体中的位错滑移，位错移动越容易，金属越软。纯铁的晶格非常规整，位错几乎畅通无阻；加入碳、铬等后，异种原子尺寸与铁不同，造成局部晶格畸变，像钉子一样钉住位错，使它难以运动，金属就变硬变强，这叫做固溶强化。析出的碳化物和晶粒细化还能进一步阻碍位错。但强度提升往往伴随塑性下降，所以钢需要淬火、回火等热处理，在强度与韧性之间取得平衡。
Metals deform mainly by the sliding of dislocations through the crystal, and the easier they move the softer the metal. Pure iron has a very regular lattice where dislocations glide almost freely; adding carbon or chromium introduces atoms of different size that distort the lattice locally, acting like nails that pin dislocations and stop them moving - solid-solution strengthening. Precipitated carbides and grain refinement pile on further obstacles. But strength usually comes at the cost of ductility, so steel is heat-treated through quenching and tempering to balance strength against toughness.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
《普通化学》（金属与合金）
General Chemistry (metals and alloys)
#合金 #位错 #固溶强化
为什么石墨烯又轻又强？
Why is graphene strong yet light?
石墨烯只有一个原子厚，碳以 sp² 杂化铺成蜂窝平面，受力时由面内共价键直接承担，不靠层间弱接合；薄到这份上裂纹与位错无处容身，强度接近本征上限而非缺陷下限。它几乎全是表面，面密度可忽略，比强度约比多数工程材料高一个数量级。但这说的是单片：宏观膜与复合材料有褶皱、滑移和界面失效，远达不到，石墨能当润滑剂也正出于此。
Graphene is one atomic layer, carbons sp²-bonded into a honeycomb plane, so loading strains those in-plane bonds directly rather than the weak join between layers, and a layer this thin leaves no room for cracks or dislocations, putting strength near the intrinsic ceiling instead of a defect-set floor. Nearly all surface, its mass per area is negligible, giving specific strength about an order of magnitude above most engineering materials. That is one clean flake: membranes and composites fold, slip between layers and fail at interfaces, and graphite is soft enough to lubricate for the same reason.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#石墨烯 #共价键 #强度
MOF 如何用于 CO₂ 捕集？
How are MOFs used for CO₂ capture?
开放金属位点和含氮基团对 CO₂ 有优先吸附（相比 N₂），可用温度或压力摆动再生，适合烟气分离。
Open metal sites and nitrogen groups preferentially adsorb CO₂ over N₂, and the material is regenerated by temperature or pressure swing.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#MOF #CO2捕集 #吸附
金属氢化物是怎么“装”住氢气的？
How do metal hydrides ‘trap’ hydrogen?
某些合金(如LaNi5)能与氢可逆地形成氢化物，常温常压下吸附、加热时再把氢释放出来，体积储氢密度高。
Alloys like LaNi5 reversibly form hydrides with hydrogen—sorbing it at ambient conditions and releasing on heating—with high volumetric density.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#金属氢化物 #储氢 #合金
MOF（金属有机框架）为什么孔体积超大且可定制？
Why do MOFs have huge, tailorable porosity?
金属节点与有机配体自组装成周期性多孔晶格，比表面积可达数千 m²/g；孔的尺寸与功能基团可由配体设计调控。
Metal nodes and organic linkers self-assemble into periodic porous lattices with surface areas over thousands of m²/g; pore size and functionality are tunable via the linker.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#MOF #多孔材料 #比表面积
形状记忆合金(如镍钛)为什么能“记”住形状？
Why can shape-memory alloys (like NiTi) ‘remember’ a shape?
温度变化时合金发生可逆的马氏体相变：低温能变形，加热回到母相就恢复原形，像有记忆一样。
A reversible martensitic phase transition lets the alloy be deformed when cold and snap back to the original ‘parent’ shape when heated.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#形状记忆 #镍钛 #相变
为什么钢化玻璃比普通玻璃结实好几倍，摔碎后还会碎成小颗粒？
Why is tempered glass several times stronger than ordinary glass, and why does it shatter into small granules?
钢化玻璃是把普通玻璃加热到接近软化点后快速均匀冷却制成的。冷却时表面先凝固、内部后收缩，结果表面形成压应力、内部形成张应力；玻璃的抗压强度远高于抗拉强度，表面的压应力像铠甲一样抵消外来的拉应力，所以更结实。一旦受冲击破裂，内部储存的张应力使整块玻璃瞬间碎成圆钝的小颗粒，而不是尖锐的大碎片，安全性因此大大提高。
Tempered glass is ordinary glass heated near its softening point and then cooled rapidly and uniformly. The surface solidifies first while the interior contracts later, leaving compressive stress in the surface and tensile stress inside; because glass resists compression far better than tension, the surface's compressive armour cancels incoming tensile stress and makes it stronger. When it finally breaks, the stored internal tension shatters the whole pane instantly into small, blunt granules rather than sharp shards - which is what makes it far safer.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#钢化玻璃 #压应力 #安全
用形状记忆合金做的眼镜架被弯折后，为什么一加热又能弹回原来的形状？
Why does a bent eyeglass frame made of shape-memory alloy spring back to its original shape when heated?
形状记忆合金（最常见的是镍钛合金）存在两种晶体结构：低温的马氏体和高温的奥氏体。常温下弯折只改变马氏体晶体的孪晶排列方式，原子没有真正滑移，变形是可逆的；加热到相变温度以上，合金转变回奥氏体，晶体恢复原本排列，宏观形状也跟着复原。这一记住高温相形状的本领来自可逆的固相相变，而不是普通金属的弹性，因此被用于牙箍、血管支架和航天机构中。
Shape-memory alloys, most commonly nitinol (nickel-titanium), have two crystal structures: martensite at low temperature and austenite at high temperature. Bending at room temperature only rearranges the twin domains of the martensite without real atomic slip, so the deformation is reversible; heating above the transformation temperature converts the alloy back to austenite, whose original atomic arrangement restores, and the frame recovers its shape. This memory of the high-temperature phase comes from a reversible solid-state phase change, not ordinary elasticity - which is why it is used in braces, vascular stents and space mechanisms.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#形状记忆合金 #相变 #镍钛
为什么灯泡灯丝用钨不用铁？
Why is the light-bulb filament tungsten, not iron?
钨是熔点最高的金属（约3422°C），高温下不熔化，蒸发也慢，适合做白炽灯丝。
Tungsten has the highest metal melting point (~3422 C), so it stays solid and slowly evaporates at filament temperatures.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#钨 #高熔点 #灯丝
为什么水泥遇水会变硬？
Why does cement harden with water?
水泥矿物与水发生水化反应，生成交织的晶体把沙石胶结。
Cement minerals hydrate, forming interlocking crystals that bind sand and stone.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#水泥 #水化 #固化
为什么陶瓷能耐高温？
Why is ceramic heat-resistant?
陶瓷由强离子键和共价键构成，熔点很高。
Ceramics use strong ionic/covalent bonds, giving very high melting points.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#陶瓷 #耐高温 #键
纳米金溶液是红色的，而大块金是黄色的，为什么缩小到纳米尺度颜色就变了？
Gold nanoparticles in solution are red while bulk gold is yellow - why does shrinking to the nanoscale change the colour?
纳米颗粒的尺寸已经小到可以和可见光波长相比，光不再被金属表面直接反射，而是激发颗粒中的自由电子集体振荡，形成局域表面等离激元共振，强烈吸收特定波长的光。金的等离激元共振落在绿光附近，吸收掉绿光后透过的光呈红色；颗粒大小、形状改变时共振波长移动，颜色也随之从红到紫、蓝变化。纳米材料比表面积巨大、表面原子占比高，所以催化活性、熔点等性质也和大块材料明显不同。
When particles shrink to sizes comparable to visible wavelengths, light no longer reflects off a flat metal surface; instead it excites collective oscillation of the free electrons inside each particle - localized surface plasmon resonance - which strongly absorbs light of a specific wavelength. Gold's resonance sits near the green, so green light is absorbed and the transmitted light looks red; changing particle size or shape shifts the resonance, marching the colour from red through purple to blue. Nanomaterials also have enormous surface area and a high fraction of surface atoms, so catalytic activity, melting point and other properties differ markedly from bulk material.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#纳米材料 #等离激元 #比表面积
为什么现代炼钢用纯氧吹炼而不用空气？
Why do modern furnaces blow pure oxygen instead of air in steelmaking?
空气里约78%是氮气，会稀释反应、降低炉温并产生氮氧化物。用纯氧脱碳更快、温度更高、钢更纯净。
Air is ~78% nitrogen, which cools the bath and forms NOx. Pure oxygen gives faster decarburization, higher temperature and cleaner steel.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#炼钢 #纯氧 #脱碳
为什么金属会导热？
Why do metals conduct heat?
金属内部自由电子能快速传递能量。
Free electrons in metals carry energy quickly.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#导热 #电子 #金属
水泥遇水为什么会变硬？
Why does cement harden when mixed with water?
水泥中的硅酸盐、铝酸盐与水发生水化反应，长出针状晶体把砂和石子“粘”成一个整体，逐渐硬化。
Cement silicates and aluminates react with water, growing needle-like crystals that bind sand and gravel into a solid mass.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#水泥 #水化 #硬化
为什么大体积混凝土浇筑时会发热？
Why does mass concrete get hot as it sets?
水泥水化是放热反应，大量水泥同时反应会积聚可观热量，大体积浇筑时散不掉，需用冷却管防止开裂。
Cement hydration is exothermic; with huge amounts of cement the heat builds up and, in mass pours, can't escape—cooling pipes prevent cracking.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#混凝土 #水化热 #开裂
黄铜(铜锌合金)为什么适合做乐器和管件？
Why is brass (copper–zinc) good for instruments and fittings?
加锌提高了强度与耐蚀性，加工也容易，而且音色明亮，所以常用于乐器和自来水零件。
Zinc raises strength and corrosion resistance, improves machinability, and gives a bright tone—hence its use in instruments and plumbing.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#黄铜 #铜锌合金 #耐蚀
碳纤维材料为什么能同时做到很轻和很强？
How can carbon-fiber materials be simultaneously so light and so strong?
碳纤维由含碳原料在高温下石墨化得到，内部是沿纤维轴向高度取向的细小石墨微晶，碳-碳共价键极其牢固且方向性好，因此沿纤维方向的抗拉强度可达钢的数倍。碳的原子量又小，密度只有钢的约四分之一，所以比强度（强度除以密度）遥遥领先。用树脂复合后，受力通过基体传递到纤维，铺层方向设计得当，就能得到又轻又强的结构件，广泛用于飞机、赛车、自行车和风电叶片。
Carbon fiber is made by graphitizing carbon-rich feedstocks at high temperature; inside, tiny graphite crystallites align tightly along the fiber axis, and carbon-carbon covalent bonds are extremely strong and highly directional, so tensile strength along the fiber can be several times that of steel. Carbon is also light, about a quarter of steel's density, so its specific strength (strength divided by density) is far ahead. Embedded in resin, loads transfer through the matrix into the fibers, and with proper ply orientation you get structural parts that are both light and strong, used in aircraft, race cars, bicycles and wind-turbine blades.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#碳纤维 #比强度 #复合材料
补牙的银汞合金为什么能用？
Why is dental amalgam usable for fillings?
汞与银锡铜粉混合成可塑体填入牙洞，随后固化变硬、耐磨又便宜；但含汞，使用时需权衡安全性。
Mercury mixed with silver–tin–copper powder forms a plastic mass that hardens in the cavity—durable and cheap, though mercury raises safety trade-offs.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#银汞合金 #补牙 #汞
为什么摸金属总觉得比木头凉？
Why does metal feel colder than wood to touch?
金属很会传热，把手上的热很快带走，所以摸起来凉凉的。木头传热慢，把手上的热留住，所以同样温度下摸起来不凉。
Metal carries heat away from your hand fast, so it feels cool even at the same temperature. Wood carries heat slowly and keeps your hand's warmth, so it feels less cold.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#金属 #凉 #传热
高炉怎样把铁矿石炼成铁？
How does a blast furnace turn iron ore into iron?
焦炭既供热又还原 Fe₂O₃，石灰石造渣除去硅铝杂质，最终得到生铁与炉渣。
Coke supplies heat and reduces Fe₂O₃, while limestone forms slag removing Si/Al impurities, yielding pig iron and slag.
难度 入门 · 适合 大众
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#高炉 #炼铁 #还原
纸是用什么做的，为什么能吸水？
What is paper made of, and why does it absorb water?
纸由木材里的纤维素纤维交织而成；纤维上大量羟基亲水，再加上孔隙的毛细作用，所以能吸水。
Paper is matted cellulose fibers from wood; their many hydrophilic hydroxyl groups plus capillary pores let it soak up water.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#纸 #纤维素 #吸水
为什么胶水能把两张纸粘在一起？
Why does glue stick two pieces of paper together?
胶水干掉以后变成一层薄薄的膜，把纸的小坑都抓住，就粘住了。胶水没干的时候只是湿湿的，等水分跑掉、膜变硬，两张纸才真正粘牢。
When glue dries it forms a thin film that grabs the tiny bumps of the paper, holding them. While wet the glue just slides, but once the water leaves and the film hardens, the papers stick firmly.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#胶水 #粘贴 #材料
共晶合金为什么熔点比纯金属低？
Why do eutectic alloys melt lower than pure metals?
两组分在共晶点同时析出，混合带来的混乱度使液相更稳定，故 Sn-Pb 共晶（183°C）低于任一组分纯金属。
At the eutectic point both components solidify together; the mixing entropy stabilizes the liquid, so Sn-Pb eutectic (183°C) melts below either pure metal.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#共晶 #焊料 #相图
为什么海绵能吸好多水？
Why can a sponge soak up so much water?
海绵里面有很多小孔洞，水就钻进这些小洞里被存起来，所以能吸好多水。这就像用许多小吸管吸水一样，是孔洞把水留住的。
A sponge has many tiny holes where water hides and gets stored, so it soaks up a lot. Like tiny straws, the holes pull water in and hold it.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#海绵 #吸水 #材料
为什么铜像放久了表面会变绿？
Why does an old copper statue turn green?
空气中的水、氧气和一点点二氧化碳和铜慢慢反应，长出一层绿色的锈，叫铜绿。铜绿其实是一层保护膜，能挡住里面的铜不再继续被腐蚀。
Air, water, oxygen and a little carbon dioxide slowly react with copper, growing a green layer called patina. The patina is actually a protective coat that shields the copper underneath from further damage.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#铜 #铜绿 #生锈
太阳能电池为什么多用硅？
Why are solar cells mostly made of silicon?
硅的带隙约1.1 eV，正好能吸收较多太阳光并转为电，而且原料(砂子)丰富、工艺成熟。
Silicon’s ~1.1 eV band gap fits the solar spectrum well and converts it to electricity; sand is abundant and the technology is mature.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#硅 #太阳能电池 #带隙
为什么舔冰棍会粘住舌头？
Why does a popsicle stick to your tongue?
舌头上的水碰到冰立刻结成薄冰，把舌头和冰棍粘在一起了。
The water on your tongue freezes at once and glues your tongue to the icy pop.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#冰棍 #结冰 #舌头
汽车轮胎为什么是黑色的？
Why are tires black?
橡胶里加了炭黑来增强耐磨和抗紫外线老化，炭黑本身就是黑色的。
Carbon black is added to reinforce rubber and resist UV aging, and it is naturally black.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#橡胶 #炭黑 #轮胎
为什么金属勺子放进热汤里很快就会烫手？
Why does a metal spoon in hot soup get hot fast?
金属里的小粒子排得很密，热量能飞快地从一头传到另一头。
Metal particles sit close together, so heat zips quickly from one end to the other.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#金属 #传热 #热
为什么皮球掉在地上会弹起来？
Why does a rubber ball bounce?
橡胶软软的又有弹性，压一下它会马上弹回原样，就把球弹起来了。这种被压扁后还能恢复形状的本领，叫做弹性。
Rubber is soft and springy, so when squashed it snaps back and bounces the ball up. This ability to return to its shape after being pressed is called elasticity.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#橡胶 #弹性 #材料
为什么青铜比纯铜更硬、更适合作兵器？
Why is bronze harder than pure copper and good for weapons?
铜里加锡形成合金后，原子大小不一、晶格被“卡住”，阻碍位错滑动，于是比软软的纯铜硬得多。
Adding tin puts differently sized atoms into copper’s lattice, pinning dislocations so the alloy is far harder than soft pure copper.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#青铜 #合金 #硬度
什么是固溶体？
What is a solid solution?
一种原子替代或填入另一种晶格（替代型或间隙型），如黄铜中锌溶入铜，改变性能却不破坏结构。
One atom substitutes into or fills another lattice (substitutional or interstitial), as zinc dissolves in copper in brass, changing properties without breaking structure.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#固溶体 #合金 #晶格
气凝胶为什么轻得能放花瓣上、还能隔热？
Why is aerogel light enough for a petal yet insulating?
它的骨架只占极少体积、孔隙率超过 90%，所以极轻；固态骨架又抑制对流与传导，是顶级隔热材料。
Its skeleton occupies tiny volume with over 90% porosity, so it is extremely light; the solid framework also blocks convection and conduction, making it a top insulator.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#气凝胶 #隔热 #低密度
电线为什么大多用铜做？
Why are most wires made of copper?
铜导电好、价格适中又容易拉成细丝，是性价比最高的导电金属之一，所以到处用它做导线。
Copper conducts well, is affordable and draws into fine wires—one of the best value conductors, so it’s used for wires everywhere.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#铜 #导电 #电线
钢、生铁和纯铁，区别主要在哪？
What mainly distinguishes steel, pig iron and pure iron?
钢是含碳约0.02%–2%的铁碳合金。碳太少太软，碳太多(像生铁)则脆，调碳量就能调出不同性能。
Steel is an iron–carbon alloy with ~0.02–2% carbon. Too little is soft, too much (like pig iron) is brittle; tuning carbon sets the properties.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#钢 #含碳量 #合金
为什么给雨鞋涂了蜡就不怕水了？
Why does wax make things waterproof?
蜡不喜欢水，水珠落在蜡上面会滚下来，不会渗进去，所以雨鞋涂了蜡就不怕水。蜡是由怕水的小分子组成的，能在表面形成一层挡雨的膜。
Wax pushes water away, so water drops roll off instead of soaking in, which is why waxed rain boots stay dry. Wax is made of water-fearing molecules that form a rain-blocking coat on the surface.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#蜡 #防水 #材料
为什么金属有光泽？
Why do metals look shiny?
金属中的自由电子能反射大部分可见光。
Free electrons in metals reflect most visible light.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#金属 #光泽 #电子
为什么纸湿了以后很容易破？
Why does wet paper tear so easily?
水钻进纸的纤维之间，把纤维间的力气冲散了，纸就变软变弱。干纸的时候纤维是紧紧手拉手的，一沾水它们就松开了。
Water sneaks between the fibers and loosens their grip, so the paper turns weak. Dry paper keeps its fibers tightly linked, but water breaks those links and the paper tears easily.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#纸 #湿 #纤维
硫化矿冶炼前为什么要焙烧？
Why roast sulfide ores before smelting?
在空气中加热把硫化物转成氧化物并放出 SO₂（可回收制酸），便于后续还原得到金属。
Heating in air converts sulfides to oxides and releases SO₂ (recovered as acid), readying the metal for reduction.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#焙烧 #硫化矿 #SO2
为什么破布树皮能变成轻薄的纸？
Why can rag and bark become thin paper?
用石灰或草木灰碱煮去除木质素等，再打浆使纤维分散，抄帘沥干、烘干成纸；蔡伦在公元105年改进推广。
Alkali cooking (lime/plant ash) removes lignin, beating disperses the fibers, then sheet-forming and drying make paper; Cai Lun improved the process around 105 AD.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Housecroft & Sharpe,《Inorganic Chemistry》第5版,Pearson,2018
C. E. Housecroft and A. G. Sharpe, Inorganic Chemistry, 5th ed., Pearson, 2018
#造纸 #碱煮 #纤维
为什么粉笔能在黑板上写出白白的字？
Why can chalk write white marks on a board?
粉笔是用软软的粉做成的，在黑板上蹭一蹭，粉就留在上面变成字。
Chalk is made of soft powder that rubs off onto the board and leaves a mark.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#粉笔 #书写 #材料
为什么纸一扯就会破，而布不容易破？
Why does paper tear easily but cloth does not?
纸的纤维短短的、互相连得松，一拉就断开；布的纤维又长又缠得紧。纸是木头打碎成的短纤维压成的，而布是把长线织在一起，所以结实得多。
Paper fibers are short and loosely linked so they snap, while cloth fibers are long and tightly woven. Paper is made of short wood pulp fibers pressed together, but cloth is long threads knitted tightly, so it is far stronger.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#纸 #纤维 #材料