# Tag Info

### Why are there exactly 5 types of two-dimensional lattices, and what distinguishes them?

First, about the black lines. I think they are helpful for the hexagonal and the rhombic lattice. For the hexagonal system, it shows you the hexagons. One hexagon contains exactly the same space as ...
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Accepted

### Do superoxide salts of heavier alkali metals contradict the principle that lattice energy depends inversely on cation-anion distance?

TL, DR: They do not contradict. Although larger ions decrease the lattice energy by increasing ion distance, it is compensated by another factor that increases the lattice energy. And like Nisarg ...
• 462
Accepted

### Do we really have technology with the resolution to distinguish between layers of single atoms of materials?

X-rays do not allow you to look at the material just like an microscope. You get the spacing information from the diffraction pattern of only crystalline materials and a lot of mathematics. On the ...
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### Stacking two square (2D) layers to make a 3D close packed structure

It's actually a sneakily disguised version of a lattice you already know. Read on ... . Let's try out the staggered square packing. The distance unit used here is the center to center distance ...
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### Stacking two square (2D) layers to make a 3D close packed structure

In the picture, the cubic face-centered packing is shown, with layers of identical atoms colored in red and blue for better contrast. The unit cell shown with thin lines is the conventional face-...
• 30.1k
Accepted

• 30.1k
1 vote

### Conventional unit cell for a hexagonal crystal system

Interestingly enough, the reason why the cell in bold is the unit-cell for the crystal is actually because the hexagonal cell has this higher symmetry you mention. To understand why, we have to ...
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