Question

Only one isotope of this element occurs in nature. one atom of this isotope has a mass of 9.123 ✕ 10-23 g. identify the element and give its atomic mass. element

Answer 1

The atom has only one isotope which means 100 % of same atom is present in nature. The atomic mass of an element is the number of times an atom of that element is heavier than an atom of carbon taken as 12. Mass of one atom of that isotope is 9.123 ✕ 10⁻²³ g, so mass of one mole of atom that is Avogadro's number of atom is 6.023 X 10²³  X 9.123 X 10⁻²³ g=54.94 g = 55 g (approximate).

So, the atom having atomic mass 55 will be Cesium (Cs). Only one isotope of Cesium is stable in nature.

Answer 2

Answer: The atomic mass of manganese element is 54.96 g/mol

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Number of particles}}{\text{Avogadro's number}}$

We are given:

Number of atoms = 1 atom

Avogadro's number = $6.022\times 10^{23}atom/mol$

Putting values in above equation, we get:

$\text{Number of moles}=\frac{1}{6.022\times 10^{23}}=1.66\times 10^{-24}mol$

Now, calculating the molar mass of element by using equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

We are given:

Given mass of element = $9.123\times 10^{-23}g$

Moles of element = $1.66\times 10^{-24}mol$

Putting values in above equation, we get:

$1.66\times 10^{-24}mol=\frac{9.123\times 10^{-23}g}{\text{Molar mass of element}}\\\\\text{Molar mass of element}=\frac{9.123\times 10^{-23}g}{1.66\times 10^{-24}mol}=54.96g/mol$

The element having molar mass as 54.96 g/mol is manganese.

Hence, the atomic mass of manganese element is 54.96 g/mol