Estimates of the radii of most metal atoms can be found. Where do these data come from? How do we know, for example, that the radius of a nickel atom is 0.1246 nm? Nickel crystallizes in a face-centered cubic unit cell with a cell-edge length of 0.3524 nm to calculate the radius of a nickel atom….
Atoms on the corners, edges, and faces of a unit cell are shared by more than one unit cell, as shown in the figure below. An atom on a face is shared by two unit cells, so only half of the atom belongs to each of these cells. An atom on an edge is shared…
Nickel is one of the metals that crystallize in a cubic closest-packed structure. When you consider that a nickel atom has a mass of only 9.75 x 10-23 g and an ionic radius of only 1.24 x 10-10 m, it is a remarkable achievement to be able to describe the structure of this metal. The obvious question…
NaCl should crystallize in a cubic closest-packed array of Cl– ions with Na+ ions in the octahedral holes between planes of Cl– ions. We can translate this information into a unit-cell model for NaCl by remembering that the face-centered cubic unit cell is the simplest repeating unit in a cubic closest-packed structure. There are four unique positions in a face-centered cubic unit cell….
The lattice points in a cubic unit cell can be described in terms of a three-dimensional graph. Because all three cell-edge lengths are the same in a cubic unit cell, it doesn’t matter what orientation is used for the a, b, and c axes. For the sake of argument, we’ll define the a axis as the vertical axis of our coordinate system, as…
The Simplest Repeating Unit in a Crystal A Three-Dimensional Graph NaCl and ZnS Measuring the Distance Between Particles Determining the Unit Cell of a Crystal Calculating Metallic or Ionic Radii Unit Cells: The Simplest Repeating Unit in a Crystal The structure of solids can be described as if they were three-dimensional analogs of a piece of wallpaper. Wallpaper has…
Geometrical Shape Crystalline Solids: Crystalline solids have a well-defined geometrical shape due to the regular arrangement of unit cells. Noncrystalline Solids: Non-crystalline solids do not have well–defined geometrical shape. Range Order Crystalline Solids: Crystalline solids have a long range order. Noncrystalline Solids: Non-crystalline solids have a short range order. Melting Point Crystalline Solids: Crystalline solids have a definite melting point. Noncrystalline Solids: Non-crystalline solids…
Crystalline Solids and Non-crystalline Solids are the two main categories of solids that show some difference between them in terms of the arrangement of the constituent particles and other properties. The key difference between crystalline solids and non-crystalline solids is that Crystalline Solids have an evenly distributed three-dimensional arrangement of atoms, ions, or molecules while Non crystalline Solids do not…