Rhenium is an excellent catalyst. Rhenium has an HCP crystal structure, an atomic radius of 0.137 nm, and a c/a ratio of 1.615. Compute the volume of the unit cell for Re. If Re is added to at 4% to Platinum what do you expect the crystal structure of the alloy to be.

8.63 × 10^-23 cm; cubic close packed structure.

Explanation:

HCP is the acronym for Hexagonal Close Packing, Rhenium,Rh has this type of structure. It was also given from the question that the atomic radius of the crystal is 0.137 nm = 1.37 × 10^-8 cm and the crystal structure has a c/a ratio of 1.615, that is, c = 1.615 a and a= 2B. To solve this question of volume computation of Rhenium unit cell, we will be using the formula below:

Volume, V= 6B^2× c√3.

Therefore, we have, V= 1.615 × 12√3 × (1.37 × 10^-8 cm)^3= 8.63 × 10^-23 cm.

===> 8.63 × 10^-23 cm.

For the solution to the second part of the question, we know that the Hexagonal Close Packing arrangements and the cubic close packed structure of Platinum has about 74% in their packing arrangements, so the addition of little Hexagonal Close Packing of Rhenium that is 4% will not affect the crystal packing of close packed structure of Platinum that much and we will be expecting a cubic close packed structure.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

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