mass ratio of atom vs subatomic particles

[aye]

can anyone tell me the ratio? like what would be the mass of an atom compared to that of an electron or positron? THanks!

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[Turkeyman]

There's not a set ratio in general, but if you were to take all the individual parts of an atom and weigh them out, and then put the atom together and weigh that, the atom itself will always weigh less. The discrepancy in mass is called the mass defect for that atom...and I don't think it's any set ratio.

The mass defect is caused by turning mass into energy that binds the atom together, that's called the binding energy.

If you plug the mass defect (weight of separate constituents summed up - mass of the atom) into e=mc^2, you'll get the binding energy.

Hoofah!

edit:

whoops, I'm not sure I really answered your question haha, but the ratios would be different for every atom if you wanted to compare the weight of a given atom to the weight of an electron or other particle ;0

 

[Shredder]

ive never heard of this as far as mcat is concerned. i think an important thing to remember when studying for it is that only so much depth is tested, and after taking practice tests and questions you begin to see what that level is. prep courses teach more in depth material than the test seems to require, and i guess they do this just in case. deciding what and what not to learn is critical though since there is only so much time, not to mention memory capacity. it is a pretty expansive test after all.

putting the mass of an electron in a denominator would yield an enormous number i would think

 

[stoleyerscrubz]

mass of one electron is about 1800 times smaller than that of a proton or neutron. So in a Hydrogen atom it would be
1800:1
proton mass:electron mass

since hydrogen atoms only have 1 proton and no neutron.

 

[Parscope]

For very basic calculations, protons and neutrons both have a mass of 1 and the electrons' mass is insignificant.