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How many atoms are<br>there in the world?

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Could you please explain density?

How many atoms would it take to create a ton?

There's a lot more to this question than first appears. There are many types of atoms and each of them has its own mass, so the answer varies depending on which atom you are talking about. Since even a tiny bit of matter has many atoms, it has become customary to use the unit "mole" to signify a standard number of atoms, namely, it is Avogadro's number which (almost) equals 6*1023, or 600,000 billion billon. If you look up the periodic table of elements, one of the numbers usually listed is the atomic mass which is the mass (in grams) of one mole of those atoms. Let's use this information for lead as an example. One ton is 2,000 pounds. 1,000 grams is 2.2 pounds. So one ton is:

2000 * (1000/2.2) = 909,091 grams

From the periodic table, one mole of lead is about 207 grams. So one ton of lead is:

909091/207 = 4,392 moles of lead atoms.

You can use this for molecules, too, which are groups of atoms bonded together to make a distinct chemical substance. A common example is water which is 2 atoms of hydrogen (1 gram per mole) and one atom of oxygen (16 grams per mole). One simply adds the atomic masses together to get the mass of one mole of water molecules, namely:

1 + 1 + 16 = 18 grams per mole

So in this case, one ton of water will give you:

909091/18 = 50,505 moles

Author:

Carl Zorn, Detector Scientist (Other answers by Carl Zorn)