Question #05458

1 Answer
Feb 21, 2016

Let's find out!


Atoms are very, very tiny things, so in order to be able to determine the mass of a single atom you need to know the mas of a mole of atoms.

A mole is simply a very, very large collection of atoms, larger enough so that the mass of one mole of atoms can have sense for us.

So, pick up a periodic table and look for copper, #"Cu"#. You will locate it in period 4, group 9. Take a look at its molar mass, which is written below the element's chemical symbol

That number tells you the mass of one mole of copper atoms, i.e. copper's molar mass. Copper has a molar mass of #"63.546 g mol"^(-1)#, which means that one mole of copper atoms will have a mass of #"63.546 g"#

Now, in order to have one mole of copper, you need to have exactly #6.022 * 10^(23)# atoms of copper - this is known as Avogadro's number.

So, if one mole of copper has a mass of #"63.546 g"# and contains #6.022 * 10^(23)# atoms of copper, you can say that one atom of copper will have a mass of

#1color(red)(cancel(color(black)("atom of Cu"))) * overbrace((1color(red)(cancel(color(black)("mole of Cu"))))/(6.022 * 10^(23)color(red)(cancel(color(black)("atoms of Cu")))))^(color(Purple)("Avogadro's number")) * overbrace("63.546 g"/(1color(red)(cancel(color(black)("mole of Cu")))))^(color(blue)("copper's molar mass")) = color(green)(1.055 * 10^(-22)"g")#

So the answer to your question is yes, one atom of copper has a mass of #1.055 * 10^(-22)"g"#.