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1. How To Calculate The Mass Of One Atom Of Oxygen
2. Mass Of One Atom Of Oxygen Is Referred
3. Mass Of One Atom Of Oxygen Is Made
4. Mass Of Oxygen Atom Kg

Atomic Mass

Mass of one atom of oxygen is (a) 23 16 g 6.023 10 × (b) 23 32 g 6.023 10 × (c) 23 1 g 6.023 10 × (d) 8u ← Prev Question Next Question → 0 votes 862 views. For example, oxygen having atomic weight of 16 amu has gram atomic mass of 16 g for one mole. One mole is nothing but 6.0231023 atoms. To find gram atomic mass of one atom, the total weight has to be divided.

Mass of atom is called atomic mass. Since, atoms are very small consequently actual mass of an atom is very small. For example the actual mass of one atom of hydrogen is equal to 1.673 x 10^-24 g. This is equal to 0.000000000000000000000001673 gram. To deal with such small nuber is very difficult. Thus for convenience relative atomic mass is used.

Carbon-12 is considered as unit to calculate atomic mass. Carbon-12 is an isotope of carbon. The relative mass of all atoms are found with respect to C-12.

One atomic mass = 1/12 of the mass of one atom of C-12.

This means atomic mass unit = 1/12th of carbon-12

Thus atomic mass is the relative atomic mass of an atom with respect to 1/12 th of the mass of carbon-12 atom. ‘amu’ is the abbreviation of Atomic mass unit, but now it is denoted just by ‘u’.

The atomic mass of hydrogen atom = 1u.

This means one hydrogen atom is 1 times heavier than 1/12^th of the carbon atom.

The atomic mass of oxygen is 16u, this means one atom of oxygen is 16 times heavier than 1/12^thof carbon atom.

Absolute mass or Actual atomic mass:

It is found that, the actual atomic mass of a carbon-12 atom is equal to `1.9926 xx 10^(-23)`g.

`:. 1u =(1.9926xx10^(-23))/12 g`

`=>1 u = 1.6605 xx 10^(-24)g`

Thus by multiplying the relative atomic mass with 1.6605 × 10^-24g we can get the absolute or actual mass of an atom.

Example (1) Find the absolute mass oxygen (O).

Solution:

The atomic mass of oxygen is 16u

We know that, `1u=1.6605xx10^(-24)`g

Therefore, Absolute mass of oxygen

`=1.6605 xx 10^(-24)xx16`g

`=26.568xx10^(-24)`g

`=2.6568 xx 10^(-25)`g

Example (2) Find the absolute mass of Sodium (Na).

Solution:

The atomic mass of Sodium = 23u

Since, `1u=1.6605xx10^(-24)`g

∴ Absolute mass of Sodium

`=1.6605xx10^(-24)xx23` g

How To Calculate The Mass Of One Atom Of Oxygen

`=38.191 xx 10^(-24)` g

`=3.8191 xx 10^(-25)` g

Example: (3) Calculate the absolute mass of hydrogen (H) atom.

Solution:

And the atomicu mass of hydrogen (H) = 1 u

∵ `1 u= 1.6605 xx 10^(-24)` g

∴ Absolute mass of Hydrogen (H)

`=1.6605 xx 10^(-24) xx 1 ` g

`=1.6605 xx 10^(-24)` g

Example:(4) Find the absolute mass of Nitrogen(N) atom

Solution:

The atomic mass of nitrogen atom = 14 u

Mass Of One Atom Of Oxygen Is Referred

∵ `1 u= 1.6605 xx 10^(-24)` g

∴ Absolute mass of Nitrogen (N)

`=1.6605 xx 10^(-24) xx 14 ` g

`=23.247 xx 10^(-24) ` g

`=2.3247 xx 10^(-25) ` g

So then, why isn't the atomic mass of Hydrogen exactly 1?

If you check a periodic table, you'll see that Hydrogen actually has a mass of 1.00794. If hydrogen is the lightest of all substances, then why not give it a mass of exactly 1 on our relative mass scale?

There are three reasons:

• First, atoms have isotopes, and these isotopes do not all have the same mass. The mass of the atoms in nature - what we use as the atomic mass - is a weighted average of all these different isotopes.
  

• The second reason is historical. Once upon a time, way back before 1961, there actually were two sets of atomic masses (though everybody called them atomic weights then). One scale was used by physicists; the other by chemists. Both were based on weights compared to Oxygen, rather than Hydrogen. Oxygen was used because it combines with a lot of things to form oxides. This made it a better choice as a standard because of the ease of chemical analysis. Oxygen was set to have an atomic mass of 16, which was just about 16 times as heavy as Hydrogen being 1. Unfortunately, Chemists picked naturally occurring Oxygen, which is a mixture of isotopes of Oxygen-16, Oxygen-17, and Oxygen-18. After all when you made an oxide of an element you would do so in naturally occurring oxygen. Physicists picked the pure isotope Oxygen-16, because they tended to make their measurements on the basis of mass spectrometry.
  Though the ratio of any two atom's masses was the same on either scale, it was horribly confusing, so in 1961, a compromise was reached. Instead of using either Hydrogen, or Oxygen as the standard, the isotope of Carbon with 6 protons and 6 neutrons in its nucleus (Carbon-12) was given a mass of exactly 12. It was a good choice, since it was in between the two previously used standards, and meant that nothing had to change too much.

• The third reason is the most important of all. If a hydrogen atom has only one proton, and carbon-12 has 6 protons and 6 neutrons to make up its mass of twelve, why isn't the mass of hydrogen 1/12 of that of carbon-12?

  Mass of 1 hydrogen atom	Mass of sub-atomic particles	Mass of 1 carbon-12 atom
  1.00794	6 protons = 6 x 1.007277 6.043662 6 neutrons = 6 x 1.008665 6.051990 6 electrons = 6 x 0.000548 0.003288 Total 12.098940	12.0 exactly

  If you think about it, Hydrogen at 1.00794 is more than 1/12 of the weight of carbon-12 (as you can see from the above table, if you multiply 12 times the mass of a single hydrogen atom it comes to more than 12). The reason for this effect is nuclear binding energy. After all, the protons in the nucleus are all positive, and so the nucleus should just repel itself apart. It doesn't of course, so something must be 'binding' it together. This nuclear binding energy makes the mass of all atoms (except hydrogen-1, which only has 1 proton) slightly lighter that what you'd get by adding up the mass of the sub-atomic particles. Einstein's famous equation E = mc² shows us that we can get the necessary binding energy from the mass of the sub-atomic particles. So the mass of any multi-nucleon atom is less than the sum of the weights of its separated parts. Its this change in mass when the nucleus changes size that is the source of the enormous amount of energy in nuclear reactions.

So we could have set hydrogen to be exactly 1, but then we'd have had to really revise the atomic weight table back in 1961. If hydrogen was assigned a mass of 1 exactly, then oxygen would have become 15.87, quite a difference from the mass chemists were using. Choosing carbon-12 as the reference standard meant the least change was necessary. Still, if you do really accurate calculations based on the old and the new scale you can see some differences. For example, on the pre-1961 atomic weight scale the molecular weight of table salt, Sodium chloride NaCl would have been 58.45. On today's scale it is 58.44. The difference is just 0.02%, so for most purposes it wouldn't matter.

Mass Of One Atom Of Oxygen Is Made

Hold it! You just used the term molecular weight. Isn't that wrong? Yes, of course it is, but for Sodium chloride, we shouldn't even use the term molecular mass. Instead we should use the term 'formula mass', because Sodium Chloride really isn't a molecule of NaCl.

Mass Of Oxygen Atom Kg

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