Final answer:
The element in the 20.0-g sample with 4.95 × 10^23 atoms is copper (Cu). To identify the element, calculate the number of moles using Avogadro's number and then the molar mass, which can be matched to an element on the periodic table.
Step-by-step explanation:
To identify the element of a 20.0-g sample that contains 4.95 × 1023 atoms, we need to use Avogadro's number, which is 6.022 × 1023 atoms per mole, and the concept of molar mass.The given sample contains 4.95 x 10^23 atoms and has a mass of 20.0 g. To identify the element, we need to calculate the molar mass using the given moles-to-mass ratio. Considering that the mass of 1 mole of Cu is approximately 64 g, a reasonable estimate for the number of atoms in the sample would be on the order of 10^22 Cu atoms. Therefore, the element in the sample is copper (Cu).
First, we determine the number of moles of atoms in the sample using the formula:
number of moles = number of atoms ÷ Avogadro's number
Then, we calculate the molar mass:
molar mass = mass of the sample ÷ number of moles
Once we find the molar mass, we match it to an element on the periodic table.