To determine the total number of valence electrons in a given amount of N3- ions, we need to calculate the number of moles of N3- ions first. Then we can multiply the number of moles by Avogadro's number to find the total number of N3- ions. Finally, we multiply the number of N3- ions by the number of valence electrons in each N3- ion.
The molar mass of nitrogen (N) is approximately 14.01 g/mol. To calculate the number of moles of N3- ions, we divide the given mass (4.2 g) by the molar mass:
Number of moles = mass / molar mass = 4.2 g / 14.01 g/mol ≈ 0.2995 mol
Next, we use Avogadro's number, which is approximately 6.022 x 10^23 particles per mole, to calculate the total number of N3- ions:
Number of N3- ions = Number of moles x Avogadro's number = 0.2995 mol x 6.022 x 10^23 ions/mol ≈ 1.803 x 10^23 ions
Finally, we multiply the number of N3- ions by the number of valence electrons in each N3- ion. The N3- ion has a total of 7 valence electrons:
Total number of valence electrons = Number of N3- ions x Number of valence electrons per ion = 1.803 x 10^23 ions x 7 electrons/ion ≈ 1.2621 x 10^24 electrons
Therefore, there are approximately 1.2621 x 10^24 valence electrons in 4.2 gm of N3- ions.