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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: zerox0o on September 03, 2009, 08:22:16 PM

Title: Is this correct?
Post by: zerox0o on September 03, 2009, 08:22:16 PM

The diameter of a certain atomic nucleus is 4.30× 10−5 pm and its mass is 4.00 x 10-25 g. What is the density of the nucleus in units of g/cm3 ? Assume the nucleus is a sphere with a volume equal to 4/3 π r3 . (Remember that the diameter is twice the radius.)

Enter a numeric answer only, no units. Use at least the correct number of significant figures. How does this compare to the bulk density of lead (11.3 g/cm3 ) ?

I got 9.615e18
Compare to lead, the atomic number is much denser.

I hope that this is the right answer. Please give me some feedbacks! thanks!

Title: Re: Is this correct?
Post by: Ida Isotope on September 03, 2009, 11:26:06 PM

Maybe you could show us how you worked it out?

Title: Re: Is this correct?
Post by: MrTeo on September 04, 2009, 07:45:57 AM

Yeah, the answer is right... i get 9.61e18 g/cm³ (remember significant figures).

This fact can be easily explained as almost all the mass of an atom is in its nucleus (which has a huge density value, as you can see), while the electrons, as the protons' mass is about 1836 bigger than theirs, occupy a large space without significant mass.