Tellurium forms a compound with fluorine in which the tellurium ion has an oxidation number of +4. Write the chemical formula of the compound. Do not include the phase designation in the answer.

Phosphorus (P) is present in a germanium (Ge) sample. Assume that one of its five valence electrons revolves in a Bohr orbit around each P+ ion in the Ge lattice. (a) If the effective mass of the electron is 0.17 me and the dielectric constant of Ge is 16, find the radius of the first Bohr orbit of the electron. (b) Ge has a band gap (Eg) of 0.65 eV. How does the ionization energy of the above electron comparing to Eg and kBT at room temperature?

Which phosphorus nitride NP ,NP^+or NP^2- would be paramagnetic

Niobium crystallizes in BCC structure and has a density of 8.55 g/cm^3. Calculate its atomic radius if its atomic mass is 93 g/mol. *

Calculate the lattice enthalpies, ΔU (also called ΔHL), of the following group 1 fluoride compounds by using the Born–Mayer equation. The radius of Na is 102 pm and the radius of F– is 133 pm. The radius of Cs is 167 pm and the radius of F– is 133 pm.

Tooth decay (dental caries) is an unpleasant fact of life. Aging, diet, and improper dental hygiene lead to the breakdown of a critical building block of teeth, hydroxyapatite (Ca5(PO4)3OH). The hydroxyapatite forms a three dimensional crystalline structure, and this structural unit is the principal component in the exterior, the enamel part of the tooth. At the same time, we often use the brightness of other people's smiles as a measure of how healthy and well-groomed they are. Discuss the pros and cons of tooth whiteners.

(1) Diamond and graphite are two minerals with identical chemical compositions, pure carbon (C). Diamond is the hardest of all minerals, and graphite is one of the softest. If their compositions are identical, why do they have such profound differences in physical properties? (2) silicon and oxygen together make up nearly 75 percent by weight of the Earth's crust. But silicate minerals make up more than 95 percent of the crust. Explain the apparent discrepancy. (3) If you were given a crystal of diamond and another of quartz, how would you tell which is diamond? (4) Would you expect minerais found on the Moon, Mars, or Venus to be different from those of the Earth's crust? Explain your answer. (5) Quartz is Si02. Why does no mineral exist with the composition Si03?

if you can. If there is not enough information to decide, choose can't decide in the element 1 2 3 description Element 1 is a hard dark-red solid. A 10. g cube of it is set on a hot plate. After 10 minutes, the temperature of the top of the cube has risen by less than 1 °C. Element 2 is a moderately soft silvery-gray solid. A 5 cm x 5 cm square of it, only 1 mm thick, is flexed slightly by hand. The sheet snaps in half. Element 3 is a moderately soft silvery-gray solid. A small cube of it is put into a ceramic crucible and heated strongly. It melts about not far above room temperature. metal or nonmetal? O metal O nonmetal O (can't decide) O metalk O nonmetal O (can't decide) O metal O nonmetal O (can't decide)

Geosciences are very versatile. This fact rests on the finding that the number of silicate minerals that make up this planet is huge. a) By means of a reaction sequence based on Lewis structures show the step-by-step formation of a tricyclosilicate starting from silicic acid, Si(OH)4! b) Explain based on your answer from Part a) why this already offers the chance to hundreds of different minerals!