Structure of Water and Hydrogen Bonding · 水的结构与氢键
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| polar molecule/ˈpəʊlə ˈmɒlɪkjuːl/ | 极性分子 | jí xìng fēn zǐ |
| electronegativity/ɪˌlektrəʊŋɡəˈtɪvɪti/ | 电负性 | diàn fù xìng |
| partial charge/ˈpɑːʃl tʃɑːdʒ/ | 部分电荷 | bù fèn diàn hè |
| hydrogen bond/ˈhaɪdrədʒn bɒnd/ | 氢键 | qīng jiàn |
| cohesion/kəʊˈhiːʒn/ | 内聚力 | nèi jù lì |
| surface tension/ˈsɜːfɪs ˈtenʃn/ | 表面张力 | biǎo miàn zhāng lì |
| adhesion/ədˈhiːʒn/ | 附着力 | fù zhuó lì |
| specific heat/spəˈsɪfɪk hiːt/ | 比热容 | bǐ rè róng |
| solvent/ˈsɒlvənt/ | 溶剂 | róng jì |
The strangest ordinary liquid
- Life started in water, and your cells are about 70% water.
- Water does things most small molecules cannot: it climbs up trees, beads on a leaf, and resists sudden temperature change.
- All of these "superpowers" come from one feature of the water molecule.
- That feature is its shape and the way it shares electrons.
最奇特的普通液体
- 生命起源于水,你的细胞大约 70% 是水。
- 水能做到大多数小分子做不到的事:它能爬上大树、在叶子上结成水珠、还能抵抗温度的骤变。
- 所有这些“超能力”都来自水分子的一个特征。
- 那个特征,就是它的形状和它共享电子的方式。
Roughly what percentage of a typical cell is water? · 典型细胞中水分的大致百分比是多少？
Cells are about 70% water — water is the medium in which the chemistry of life happens. · 细胞约含**70%**的水——水是生命化学发生的介质。
Water is a polar molecule
- Water is $\text{H}_2\text{O}$: one oxygen joined to two hydrogens in a bent shape.
- Oxygen has a stronger pull on electrons — a higher electronegativity 电负性 — than hydrogen.
- So the shared electrons sit closer to the oxygen.
- This gives oxygen a small negative partial charge 部分电荷 and each hydrogen a small positive one.
- A molecule with separated charge like this is a polar molecule 极性分子.
水是极性分子
- 水是 $\text{H}_2\text{O}$:一个氧连着两个氢,呈弯曲的形状。
- 氧对电子的吸引力——也就是电负性(electronegativity)——比氢强。
- 所以共享的电子更靠近氧。
- 这让氧带上一点点负的部分电荷(partial charge),每个氢带上一点点正电荷。
- 像这样电荷分离的分子,就是极性分子(polar molecule)。
Why is a water molecule polar · 两极化? · 为什么水分子是极性的？
Oxygen has a higher electronegativity, so the electrons sit closer to it — giving oxygen a partial negative and the hydrogens a partial positive charge. · 氧具有更高的电负性，因此电子更靠近氧——使氧带部分负电荷，氢带部分正电荷。
Opposite charges pull: hydrogen bonds
- The positive H of one water molecule is attracted to the negative O of another.
- This weak attraction is a hydrogen bond 氢键.
- Each water molecule can hydrogen-bond to several neighbours at once.
异电相吸:氢键
- 一个水分子带正电的 H,会被另一个水分子带负电的 O 吸引。
- 这种微弱的吸引就是氢键(hydrogen bond)。
- 每个水分子可以同时与好几个邻居形成氢键。
Sticking together and to other things
- Cohesion 内聚力 is water sticking to itself — hydrogen bonds hold the molecules together.
- Cohesion creates surface tension 表面张力, letting insects walk on a pond.
- Adhesion 附着力 is water sticking to other surfaces.
- Together, cohesion and adhesion pull water up narrow tubes (capillary action), helping water rise in a plant.
与自己、与别人都粘在一起
- 内聚力(cohesion)是水粘住自己——氢键把水分子拉在一起。
- 内聚力产生表面张力(surface tension),让昆虫能在水面上行走。
- 附着力(adhesion)是水粘住其他表面。
- 内聚力和附着力一起把水拉上细管(毛细作用),帮助水在植物体内上升。
Water sticking to itself is called . · 水附着于自身称为。
Cohesion · 内聚力 is water molecules holding onto each other through hydrogen bonds; sticking to other · 相反 surfaces is adhesion. · 内聚力 (cohesion) 是水分子通过氢键相互吸附；附着于其他表面则是附着力 (adhesion)。
A single hydrogen bond is weak — far weaker than the bonds inside the molecule. Water's power comes from having a huge number of them, constantly breaking and re-forming.
单独一条氢键是很弱的——远比分子内部的化学键弱得多。水的力量来自它拥有极其大量的氢键,不断断裂又重新形成。
A single hydrogen bond is stronger than the bond holding an O and H together inside a water molecule. · 单个氢键比水分子内部 O-H 键更强。
A single hydrogen bond is weak · 弱效. Water is powerful because it has an enormous number of them. · 单个氢键是弱的。水的力量在于其拥有巨大的数量。
Select all · 所有 the properties of water that come from hydrogen bonding. · 选择所有由氢键引起的水的性质。
Cohesion, high specific heat, and solvent behaviour all come from hydrogen bonding. Being made of H and O is just its composition. · 内合力、高比热容和溶剂行为均源于氢键。由 H 和 O 组成仅是其成分。
Water resists temperature change
- Water has a high specific heat 比热容: it takes a lot of energy to warm it up.
- The energy first goes into breaking hydrogen bonds, not into raising the temperature.
- This buffers cells and whole oceans against sudden temperature swings.
- Water is also an excellent solvent 溶剂 — its polar molecules surround and dissolve other polar and charged substances.
水能抵抗温度变化
- 水有很高的比热容(specific heat):要把它加热需要很多能量。
- 能量首先用来打断氢键,而不是用来升高温度。
- 这让细胞乃至整个海洋都能缓冲温度的骤变。
- 水还是极好的溶剂(solvent)——它的极性分子会包围并溶解其他极性和带电的物质。
Will it dissolve in water? · 它会溶解在水中吗？
Sort substances by whether water — a polar solvent — can dissolve them. · 根据水——一种极性溶剂——能否溶解物质来对物质进行分类。
Why does sweating cool you down?
- To evaporate, water molecules must break their hydrogen bonds — which takes energy.
- They take that energy (as heat) from your skin.
- So as sweat evaporates, it carries heat away and your body cools.
出汗为什么能让你降温?
- 要蒸发,水分子必须打断它们的氢键——这需要能量。
- 它们从你的皮肤上取走这些能量(以热的形式)。
- 所以当汗水蒸发时,它带走了热量,你的身体就凉下来了。
Sweating cools you because evaporating water... · 出汗能降温是因为蒸发的水……
Evaporation must break hydrogen bonds, which needs energy. That energy is taken as heat from your skin, cooling you. · 蒸发必须打破氢键，这需要能量。该能量作为热量从皮肤带走，从而降温。
Water is a polar molecule, so its molecules form hydrogen bonds. Those bonds explain cohesion, adhesion, surface tension, a high specific heat, and water's power as a solvent — the properties that make life possible.
水是极性分子,所以它的分子之间会形成氢键。这些氢键解释了内聚力、附着力、表面张力、高比热容,以及水作为溶剂的强大能力——正是这些性质让生命成为可能。