Why in periodic table normally we have elements with FCC and HCP structure?

In summary, the arrangement of atoms in a crystal lattice is determined by several factors, including atomic size, electronic structure, and interatomic forces. This results in some elements having a FCC structure and others having a HCP structure. There is no clear pattern or trend in the elements that have these structures, but smaller atomic radii and higher electronegativities tend to favor HCP while larger atomic radii and lower electronegativities favor FCC. Some elements can exist in both structures, such as titanium, and the crystal structure can greatly affect the properties of the element. The crystal structure can also be changed by altering conditions or applying external forces, leading to a phase change.
  • #1
swapneel5
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0
what is basic principle followed by atoms to arrange in basic structure?
 
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  • #2
Minimizing the energy as much as possible! Close packing as in HCP and FCC seems to do the job very well. However, for some elements due to subtle electronic structure details, minimizing the energy stablizes BCC and in one case (alpha polonium) stablizes the simple cubic structure.
 

1. Why do some elements have FCC (face-centered cubic) structure while others have HCP (hexagonal close-packed) structure?

The arrangement of atoms in a crystal lattice is determined by the size and shape of the atoms, as well as the strength of the atomic bonds. For some elements, the most energetically favorable arrangement is FCC, while for others it is HCP. Factors such as atomic radius, electronic structure, and interatomic forces all play a role in determining the preferred crystal structure for each element.

2. Are there any patterns or trends in the elements that have FCC versus HCP structure?

There is no clear pattern or trend in the elements that have FCC versus HCP structure. However, elements with smaller atomic radii and higher electronegativities tend to favor HCP structure, while elements with larger atomic radii and lower electronegativities tend to favor FCC structure.

3. Can elements have both FCC and HCP structures?

Yes, some elements can exist in both FCC and HCP structures, depending on the conditions under which they are formed. For example, titanium can exist in both FCC and HCP structures at different temperatures and pressures.

4. Does the crystal structure of an element affect its properties?

Yes, the crystal structure of an element can greatly affect its properties, such as density, strength, and conductivity. For example, HCP metals tend to be stronger and more ductile than FCC metals, and therefore are often used in structural applications.

5. Can the crystal structure of an element be changed?

Yes, the crystal structure of an element can be changed by altering the conditions under which it is formed or by applying external forces, such as pressure or temperature. This can result in a phase change, where the element transforms from one crystal structure to another.

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