# How many atoms of neon are in 5.9 grams of neon?

##### 1 Answer

#### Explanation:

The idea here is that you need to use neon's *molar mass*, which tells you what the mass of **one mole** of the element is, to determine how many moles you have in that

Once you know how many moles you have, you can use **Avogadro's number** to find the number of atoms.

So, neon has a molar mass of **every mole** of neon has a mass of

Your sample of neon will thus contain

#5.9color(red)(cancel(color(black)("g"))) * "1 mole Ne"/(20.18color(red)(cancel(color(black)("g")))) = "0.2924 moles Ne"#

Now, you know that *one mole* of any element contains exactly

Well, if one mole contains that many atoms, it follows that you sample will contain

#0.2924color(red)(cancel(color(black)("moles Ne"))) * (6.022 * 10^(23)"atoms of Ne")/(1color(red)(cancel(color(black)("mole Ne")))) = color(green)(1.8 * 10^(23)"atoms of Ne")#

The answer is rounded to two sig figs, the number of sig figs you have for the mass of the sample.