Very small crystals composed of 1000 to 100,000 atoms, called quantum dots, are
ID: 817415 • Letter: V
Question
Very small crystals composed of 1000 to 100,000 atoms, called quantum dots, are being investigated for use in electronic devices. A- A quantum dot was made of solid silicon in the shape of a sphere, with a diameter of 9 Calculate the mass of the quantum dot, using the density of silicon (2.3 g/cm^3) b- How many silicon atoms are in the quantum dot? nm Very small crystals composed of 1000 to 100,000 atoms, called quantum dots, are being investigated for use in electronic devices. A quantum dot was made of solid silicon in the shape of a sphere, with a diameter of 9 Calculate the mass of the quantum dot, using the density of silicon (2.3 g/cm^3) How many silicon atoms are in the quantum dot? The density of germanium is 5.325 g/cm^3 If you made a 9 quantum dot of germanium how many GE atoms would it contain? Assume the dot is sphericalExplanation / Answer
) Since density = mass/volume
density times volume = mass and
volume = mass/density =6.996 x 10^(-19) grams/ 2.3 grams/cm^3
= 3.04162 x 10^(-19) cubic centimeterss
= 3.042 x 10^(-19) cc if we must round to 4 sig figs, 3 to right of decimal
A mole, however is 6.022 x 10^23 atoms
so the mass of this dot is
28.0855 grams/mole x [1 mole]/ [6.022 x10^23]atoms x [1.500 x 10^4]atoms/ 1
=6.99572 x 10^(-19) grams = 6.996 x 10^(-19) grams
to 4 significant figures
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