# One uranium atom has a mass of 3.95 x 10^-22 grams. How would you work out an estimate for the number of uranium atoms in 1 kg of uranium?

Dec 12, 2016

Well, divide $\text{one kilogram}$ by the mass of one uranium atom......

#### Explanation:

And thus, $\frac{1000 \cdot g}{3.95 \times {10}^{-} 22 \cdot g \cdot {\text{atom}}^{-} 1}$

$=$ $\text{A large number of uranium atoms.}$

This is a molar quantity of $\frac{1000 \cdot g}{238.1 \cdot g \cdot m o {l}^{-} 1} \cong 4 \cdot m o l$.

And so there are approx. $4 \times {N}_{A}$ $\text{uranium atoms}$, where ${N}_{A} = \text{Avogadro's number, } 6.022 \times {10}^{23}$.