Hydrogen or Helium?

Chemistry Level 2

Which of the following is heavier out of the two

  • The total sum of atomic masses of 4 hydrogen atoms
  • The atomic mass of 1 helium atom?

Details:

  • The atomic mass should not be approximated to any nearest decimal place (specially not up until 10 places).
  • Atomic mass refers to the average atomic mass calculated keeping in mind the individual masses of all isotopes and their respective abundancies in nature.
Four hydrogen atoms Both have exactly the same mass One helium atom

Tapas Mazumdar by Tapas Mazumdar , 20, India

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1 solution

Dhruv Somani
Mar 15, 2017

Do not forget the electrons. They have a mass.

0 Helpful 0 Interesting 0 Brilliant 1 Confused

Regardless of the 2 electron drawback of helium, it still contains two neutrons to fill the gap. While four hydrogen atoms may have together of 4 electrons, they do not have any neutrons. And you should know that mass of electron is very small compared to that of the neutrons. In my opinion, this isn't a good reason for this phenomenon.

So, as far as the actual data goes,

Mass of proton = 1.007 u

Mass of neutron = 1.008 u

Mass of electron = 0.0005 u

For 1 hydrogen, mass = 1.0075 u

For 4 hydrogens, mass = 4.03 u.

For one helium, mass = 4.031 u

Which is definitely not correct.

Hint: What happens when four hydrogen atoms fuse together?

Tapas Mazumdar - 4 years, 2 months ago

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@Tapas Mazumdar Please tell the correct reason , I think I got it correct with a wrong reasoning.

Ankit Kumar Jain - 3 years, 3 months ago

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