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Describe the crystal structure of Pt, which crystallizes with four equivalent metal atoms in a cubic unit cell. This structure of platinum is a face-centered cubic. There is one-eighth atom at each of the eight corners of the cube and one-half atom on each of the six faces of the cube.
- 4.1: Unit Cells
Unit Cells of Metals. The structure of a crystalline solid,...
- 12.1: Crystal Lattices and Unit Cells
The Unit Cell. This section deals with the geometry of...
- 4.1: Unit Cells
General unit cell problems. Go to the body-centered cubic problems. Go to the face-centered cubic problems. Return to the Liquids & Solids menu. Problem #1: Many metals pack in cubic unit cells. The density of a metal and length of the unit cell can be used to determine the type for packing.
Unit Cells of Metals. The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions.
The Unit Cell. This section deals with the geometry of crystaline systems. These could describe how metal atoms pack when they form metallic solids, or how ions pack when they form ionic crystals. We will look at the ionic structures in the next section, and here focus on the generic unit cell and it's application to metallic structures.
Go to the general unit cell problems. Return to the Liquids & Solids menu. Problem #1: The edge length of the unit cell of Ta, is 330.6 pm; the unit cell is body-centered cubic. Tantalum has a density of 16.69 g/cm 3. (a) calculate the mass of a tantalum atom. (b) Calculate the atomic weight of tantalum in g/mol. Solution: 1) Convert pm to cm:
Go to some general unit cell problems. Return to the Liquids & Solids menu. Problem #1: Palladium crystallizes in a face-centered cubic unit cell. Its density is 12.023 g/cm 3. Calculate the atomic radius of palladium. Solution: 1) Calculate the average mass of one atom of Pd: 106.42 g mol¯ 1 / 6.022 x 10 23 atoms mol¯ 1 = 1.767187 x 10¯ 22 g/atom.
17 PRACTICE PROBLEM. For the simple cubic unit cell, identify each of the following: i. the number of atoms. ii. fraction of each atom in the cube. iii. Total number of atoms inside the cube. 6. Previous Topic: Crystalline Solids. Next Topic: Body Centered Cubic Unit Cell.
