# Relative atomic massWatch

#1
RElative atomic and molecular masses are measured on a scale in which 12c = 12 excatly.. What does this mean and why is that relative atomic mass is said to be a more useful concept than atomic mass.. both of them are the same thing arent they ..i mean both refer to the number of protons and neutrons !!
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#2
help !!!!
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13 years ago
#3
(Original post by e-n-i-g-m-a)
help !!!!
I'm not 100% sure, so maybe someone else can verify what I'm about to say.

I think the atomic mass refers to a single atom. I might pick up a single carbon atom and it might contain 6-Protons and 6-Neutrons. I would say it has an atomic mass of 12. I might pick up another atom with 6-Protons and 7-Neutrons. That would have an atomic mass of 13. (Both those atoms are naturally occurring isotopes of Carbon).

It's not useful because we never pick up just one atom of something. We pick up loads (mass in g X 6.022X10^23) and it contains a mixture of isotopes. Relative atomic mass takes into account these isotopes and gives a weighted mean (relative to 1/12 the mass of a carbon-12 atom). Atomic mass refers to a particular isotope only (not useful).
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#4
i dont get it !!!
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13 years ago
#5
(Original post by e-n-i-g-m-a)
i dont get it !!!
First of all do you know what isotopes are?
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13 years ago
#6
(Original post by e-n-i-g-m-a)
i dont get it !!!
First of all do you know what isotopes are?
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13 years ago
#7
the relative atomic mass of an element is the weighted average mass of the atoms of that element compared to one twelfth the mass of a carbon 12 atom. Bascially carbon twelve is sued to compare everything The relative molecular mass is the sum of all the relative atomic masses of an elemtns constituted atoms. I suggest you try wikipedia or consult your textbooks for a better understanding. its quite straightforward really
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13 years ago
#8
the relative atomic mass of an element is the weighted average mass of the atoms of that element compared to one twelfth the mass of a carbon 12 atom. Bascially carbon twelve is sued to compare everything The relative molecular mass is the sum of all the relative atomic masses of an elemtns constituted atoms. I suggest you try wikipedia or consult your textbooks for a better understanding. its quite straightforward really
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13 years ago
#9
Naaaaaaaaaaaabid
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13 years ago
#10
Naaaaaaaaaaaabid
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13 years ago
#11
(Original post by rahmed)
Naaaaaaaaaaaabid
cmpletely inappropriate for this thread i should have you warned *moves mouse and clikcs on bad reputation points*
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13 years ago
#12
(Original post by rahmed)
Naaaaaaaaaaaabid
cmpletely inappropriate for this thread i should have you warned *moves mouse and clikcs on bad reputation points*
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13 years ago
#13
(Original post by e-n-i-g-m-a)
RElative atomic and molecular masses are measured on a scale in which 12c = 12 excatly.. What does this mean
It is just like a benchmark for comparrison. Its purpose is to enable chemists and the like to be able to compare the weight of an atom with a known and respected weight. Say there was no benchmark, and nothing was "relative" to anything else, you wouldn't know what was heavy, what was light, etc... For example, when a person weighs themself, they only know that they are overweight because of a benchmark which has been set to tell them what the average weight is for their age, height etc. This sort of answers your second question as well...
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13 years ago
#14
(Original post by e-n-i-g-m-a)
RElative atomic and molecular masses are measured on a scale in which 12c = 12 excatly.. What does this mean
It is just like a benchmark for comparrison. Its purpose is to enable chemists and the like to be able to compare the weight of an atom with a known and respected weight. Say there was no benchmark, and nothing was "relative" to anything else, you wouldn't know what was heavy, what was light, etc... For example, when a person weighs themself, they only know that they are overweight because of a benchmark which has been set to tell them what the average weight is for their age, height etc. This sort of answers your second question as well...
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13 years ago
#15
i should think that just 'atomic mass' is measured in kgs (just like u need those of protons with e=mc2)
relative atmic mass is measured i think saying that mass of C12 = 12 amu
as it must provide the most exact value compared to others
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13 years ago
#16
One atomic mass unit, u, is equal to 1.66E-27 kg (1.66*10^-27).

It is a convinient unit of mass when you are talking about individual atoms or molecules. You should remember that for molecules that weigh u, one mole of them will weigh u kg.

I believe that using these units will also allow you to calculate energy in eV without any conversions.
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13 years ago
#17
Do not confuse Atomic mass, Relative Atomic mass, Atomic Mass Unit and Mass.

The OP was right in saying they are similar.
http://en.wikipedia.org/wiki/Atomic_mass

Not that it will help you will your original question - but it will show you Atomic mass is not in kg!! Atomic mass like relative atomic mass has no units.

That link claims "atomic mass" and "relative atomic mass" are the same thing. I'm not so sure if we are to believe the original question is valid. I think atomic mass does not take different isotopes into account but relative atomic mass does.
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