Chemistry Examples

$H e$

Step 1

To calculate the mass of a single atom, first look up the atomic mass of $H e$ from the periodic table. This is also the mass in grams of 1 mole of $H e$ .

$4$

Step 2

Use Avogadro's number to find the mass of a single atom.

$\frac{4}{6.022 \cdot 10^{23}}$

Step 3

Simplify the expression.

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Step 3.1

Divide using scientific notation.

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Step 3.1.1

Group coefficients together and exponents together to divide numbers in scientific notation.

$(\frac{4}{6.022}) (\frac{1}{10^{23}})$

Step 3.1.2

Divide $4$ by $6.022$ .

$0.66423115 \frac{1}{10^{23}}$

Step 3.1.3

Move $10^{23}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$0.66423115 \cdot 10^{- 23}$

Step 3.2

Move the decimal point in $0.66423115$ to the right by $1$ place and decrease the power of $10^{- 23}$ by $1$ .

$6.64231152 \cdot 10^{- 24}$