Question

How many atoms are in 3.5 grams of silicon?

Answer 1

Hint: Silicon is the element of group 14 of the p-block and it comes in the third period, so its atomic number is 14 and its atomic mass is 28.0855 g. To find the number of atoms, multiply Avogadro's number with the given mass and then divide it with the atomic mass of the element.

Complete step by step answer:
- Silicon is the element of group 14 of the p-block and it comes in the third period, so its atomic number is 14 and its atomic mass is 28.0855 g.
- The atomic mass of any element is equal to one mole of that element, and we know that one mole of any substance will have $6.022\text{ x 1}{{\text{0}}^{23}}$ atoms, and this number is known as Avogadro’s number.
- So, 1 mole of silicon will have a mass of 28.0855 g and the number of atoms will be $6.022\text{ x 1}{{\text{0}}^{23}}$.
- We have to find the number of atoms in 3.5 grams of silicon. As we know 28.0855 grams of silicon have $6.022\text{ x 1}{{\text{0}}^{23}}$ atoms, we can calculate the number of atoms in one gram by dividing the number of atoms with mass, we get:
- $=\dfrac{6.022\text{ x 1}{{\text{0}}^{23}}}{28.0855}=2.144\text{ x 1}{{\text{0}}^{22}}$
So, one gram of silicon has $2.144\text{ x 1}{{\text{0}}^{22}}$, therefore we can calculate the number of atoms in 3.5 grams of silicon by multiplying 3.5 with the given value, we get:
$2.144\text{ x 1}{{\text{0}}^{22}}\text{ x 3}\text{.5 = 7}\text{.505 x 1}{{\text{0}}^{22}}$
Therefore, there are $\text{7}\text{.505 x 1}{{\text{0}}^{22}}$ atoms in 3.5 grams of silicon.

Note: Avogadro's number is the same for all elements, molecules, and compounds or we can say that 1 mole of the atom will have Avogadro's number of atoms and 1 mole of molecules will have Avogadro's number of molecules.