# Question #3da24

Jun 11, 2015

One atom of copper has a mass of $1.06 \cdot {10}^{- 22} \text{g}$.
One gram of copper contains $9.47 \cdot {10}^{21} \text{atoms of copper}$

#### Explanation:

The be able to determine the mass of an individual copper atom, you need to use copper's molar mass.

Copper's molar mass expresses the mass of 1 mole of copper atoms. One mole of any substance contains exactly $6.022 \cdot {10}^{23}$ atoms or molecules of that substance - this is known as Avogadro's number.

In your case, 1 mole of copper will contain $6.022 \cdot {10}^{23}$ atoms of copper. So, copper's molar mass is equal to 63.546 g.

In other words, $6.022 \cdot {10}^{23}$ atoms of copper have a mass of 63.456 g. In order to get the mass of an individual copper atom, divide this mass by how many copepr atoms are in 1 mole.

$1 \cancel{\text{copper atom") * "63.456 g"/(6.022 * 10^(23)cancel("copper atoms")) = color(green)(1.08 * 10^(-22)"g}}$

In order to get how many copper atoms are in one gram of copper, you can write

$1 \cancel{\text{g copper") * (6.022 * 10^(23)"atoms of copper")/(63.546cancel("g")) = color(green)(9.47 * 10^(21)"atoms}}$