Structure of Ionic Solids · 离子固体的结构
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| crystal lattice/ˈkrɪstl ˈlætɪs/ | 晶格 | jīng gé |
| lattice energy/ˈlætɪs ˈenədʒi/ | 晶格能 | jīng gé néng |
A perfect repeating grid
- Table salt crystals have flat faces and sharp corners.
- Zoom in and you find a grid that repeats forever.
- Positive and negative charges alternate like a 3D checkerboard.
- That orderly pattern gives salt its tough, brittle nature.
完美的重复网格
- 食盐晶体有平整的面和锐利的角。
- 放大来看,你会发现一个永远重复的网格。
- 正负电荷交替排列,像三维的棋盘。
- 那种有序的图案赋予盐坚硬而脆的本性。
The lattice
- An ionic solid is a crystal lattice 晶格 of alternating positive and negative ions.
- Each ion is surrounded by neighbours of the opposite charge.
- Strong electrostatic attraction locks the whole grid together.
晶格
- 离子固体是正负离子交替排列的晶格。
- 每个离子都被异号电荷的邻居包围。
- 强静电吸引把整个网格锁在一起。
In an ionic lattice, each ion is surrounded by ions of the opposite charge. · 在离子晶格中，每个离子都被带相反电荷的离子包围。
Alternating opposite charges maximise attraction and stability. · 交替排列的相反电荷最大化了吸引力和稳定性。
Lattice energy
- The lattice energy 晶格能 is the energy holding the lattice together.
- Higher charges and smaller ions give stronger attraction and higher lattice energy.
- This is what sets the melting point.
晶格能
- 晶格能是维系晶格的能量。
- 电荷更高、离子更小,吸引更强,晶格能更高。
- 这决定了熔点。
Which ionic compound has the higher lattice energy? · 哪种离子化合物的晶格能更高？
Larger charges attract far more strongly, so MgO has the higher lattice energy. · 更大的电荷吸引力强得多，因此MgO具有更高的晶格能。
A higher lattice energy generally means a higher melting point. · 较高的晶格能通常意味着较高的熔点。
More energy holds the lattice, so more heat is needed to break it apart. · 更多的能量束缚着晶格，因此需要更多热量来破坏它。
Lattice energy increases when the ion charges get ____. · 当离子电荷变____时，晶格能增加。
Stronger charges attract more, raising the lattice energy. · 更强的电荷吸引更多，提高了晶格能。
Why ionic solids behave as they do
- High melting points: the strong grid is hard to break apart.
- Brittle: shift a layer and like charges meet and repel, cracking it.
- They conduct only when molten or dissolved, when the ions can move.
离子固体为何如此表现
- 高熔点:强大的网格很难被拆开。
- 脆:让一层滑动,同号电荷相遇并排斥,把它裂开。
- 只有熔化或溶解时才导电,那时离子才能移动。
Inside an ionic solid · 离子固体内部
Oppositely charged ions pack into a giant repeating lattice held by electrostatic forces. · 带相反电荷的离子堆积成由静电力维持的巨大重复晶格。
An ionic solid conducts electricity... · 离子固体导电...
Ions must be free to move -- that happens when melted or dissolved. · 离子必须能够自由移动——这在熔化或溶解时发生。
Why are ionic solids brittle? · 为什么离子固体是脆性的？
A small shift brings like charges together; their repulsion cracks the crystal. · 微小位移使同种电荷靠近；它们的排斥力导致晶体开裂。
Which has the higher lattice energy, $\text{NaCl}$ or $\text{MgO}$?
- MgO has $2+$ and $2-$ ions; NaCl has $1+$ and $1-$.
- Bigger charges mean much stronger attraction, so MgO wins and melts far hotter.
$\text{NaCl}$ 和 $\text{MgO}$ 哪个晶格能更高?
- MgO 有 $2+$ 和 $2-$ 离子;NaCl 是 $1+$ 和 $1-$。
- 电荷更大意味着吸引强得多,所以 MgO 胜出,熔点也高得多。
Ionic solids do not conduct electricity as solids -- the ions are locked in place; they conduct only once melted or dissolved. Higher ion charge raises lattice energy far more than small size differences do. And the brittleness comes from the lattice: a small shift lines up like charges, which repel and shatter it.
离子固体在固态时不导电——离子被锁在原位;只有熔化或溶解后才导电。离子电荷更高对晶格能的提升,远大于微小尺寸差异带来的影响。而脆性来自晶格:小小的滑动会使同号电荷对齐,它们相斥并把晶体裂开。
An ionic solid is a crystal lattice of alternating ions held by strong electrostatic attraction. Its lattice energy -- larger for higher charges and smaller ions -- gives it a high melting point. It is brittle and conducts only when molten or dissolved, once the ions are free to move.
离子固体是正负离子交替、靠强静电吸引维系的晶格。它的晶格能——电荷越高、离子越小则越大——赋予它高熔点。它脆,且只有在熔化或溶解、离子能自由移动时才导电。