Atomic Mass: Helium-4 Nucleus Contribution

In summary, the fraction of a helium-4 atom's mass contributed by its nucleus is 0.26729986392797124965341901615185.
  • #1
AryaUnderfoot
17
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Homework Statement


The mass of a helium-4 atom is 6.64648310224 g, and each of its two electrons has a mass of 9.10939310228 g. What fraction of this atom’s mass is contributed by its nucleus?

Homework Equations


fraction of mass = mass of nucleus/mass of atom

The Attempt at a Solution


I suppose I should calculate the mass of nucleus first. But I only have the mass of the electrons, no mass of neutron, also no density...
 
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  • #2
Mass of nucleus = 6.64648310224
Mass of electrons = 9.10939310228 * 2
Mass of atom = 9.10939310228 * 2 + 6.64648310224 = 24.8652693068

Fraction of mass = mass of nucleus/mass of atom = 6.64648310224/24.8652693068 = 0.26729986392797124965341901615185

But the only problem is your data.
The masses of electron is not more than that of proton. And the mass of proton is too much.
I think you forgot to multiply the masses with power of 10s.
Well, this is the solution. Solve it in this way after you correct the data.
 
  • #3
AryaUnderfoot said:
9.10939310228 g

That's incorrect on at least two accounts. First, digits after 9.1093 are wrong, second, the end should read not "28" but "e-28" - and this "e-" is what makes the most important difference.
 
  • #4
Where is this question from? I find it hard to believe that these masses are known to anything like 12 significant figures.
 
  • #5
epenguin said:
Where is this question from? I find it hard to believe that these masses are known to anything like 12 significant figures.

9.10938356(11)×10−31 kg, if you copy digits only you will get even 13 sigfigs :wink:
 
  • #6
Aryamaan Thakur said:
Mass of nucleus = 6.64648310224
Mass of electrons = 9.10939310228 * 2
Mass of atom = 9.10939310228 * 2 + 6.64648310224 = 24.8652693068

Fraction of mass = mass of nucleus/mass of atom = 6.64648310224/24.8652693068 = 0.26729986392797124965341901615185

But the only problem is your data.
The masses of electron is not more than that of proton. And the mass of proton is too much.
I think you forgot to multiply the masses with power of 10s.
Well, this is the solution. Solve it in this way after you correct the data.
Ohh! I did a mistake
I thought 6.64648310224 is the mass of nucleus.

Correcting it!
Now,
Mass of nucleus = mass of atom - mass of electrons
And after you find it divide it with the mass of atom.

I hope you've verified the data.
 
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  • #7
10-27 kg is not the mass of the proton nor any nucleus.
 
  • #8
Aryamaan Thakur said:
Ohh! I did a mistake
I thought 6.64648310224 is the mass of nucleus.

Correcting it!
Now,
Mass of nucleus = mass of atom - mass of electrons
And after you find it divide it with the mass of atom.

I hope you've verified the data.
Ah, my bad. I forgot the significant number behind the values..I got it now. Thanks!

And also sorry for late reply ^^
 

1. What is the atomic mass of a Helium-4 nucleus?

The atomic mass of a Helium-4 nucleus is 4 atomic mass units (amu).

2. How does the Helium-4 nucleus contribute to the atomic mass of an atom?

The Helium-4 nucleus contributes to the atomic mass of an atom by accounting for approximately 99.9% of its mass. This is because the nucleus contains protons and neutrons, which are much heavier than the electrons that orbit the nucleus.

3. How is the atomic mass of Helium-4 calculated?

The atomic mass of Helium-4 is calculated by adding the number of protons and neutrons in the nucleus. Since Helium-4 has 2 protons and 2 neutrons, its atomic mass is 4 amu.

4. Why is Helium-4 used as a standard for atomic mass?

Helium-4 is used as a standard for atomic mass because it is the most abundant isotope of Helium and is present in most natural sources. It also has a simple atomic structure, making it easier to study and measure.

5. How does the atomic mass of Helium-4 compare to other elements?

The atomic mass of Helium-4 is relatively small compared to other elements. For example, the atomic mass of Carbon-12 is 12 amu, which is three times larger than the atomic mass of Helium-4. This is due to the fact that Carbon-12 has six protons and six neutrons in its nucleus, while Helium-4 only has two of each.

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