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Miss Tiffany
Guest
Hydrogen-1.008 Lithium-6.941 Sodium-22.990 Potassium-39.098
Why the atomic masses of the elements above are not whole numbers?
Why the atomic masses of the elements above are not whole numbers?
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anoman5000
New member
the numbers are not exact masses but rather the weighted average of the total possible masses of that element.
for example,
hydrogen can come in three types: atoms with mass 1amu, 2amu, or 3amu.
but since more than 99% of all hydrogen atoms have a mass of 1amu, the value given for the mass of hydrogen is very close to 1. the 0.008 comes from the factoring in of the other two masses.
same goes for the other elements. if you round the numbers, that's the most common mass of that element.
for example,
hydrogen can come in three types: atoms with mass 1amu, 2amu, or 3amu.
but since more than 99% of all hydrogen atoms have a mass of 1amu, the value given for the mass of hydrogen is very close to 1. the 0.008 comes from the factoring in of the other two masses.
same goes for the other elements. if you round the numbers, that's the most common mass of that element.
atomic masses are the weighted average of the masses of all isotopes for that element.
Hydrogen, for example, has 3 isotopes: Hydrogen, Deuterium, and Tritium. Normal Hydrogen has a mass of 1, deuterium a mass of 2, and tritium a mass of 3. The regular hydrogen is the most abundant by far, that is why the mass is only slightly over 1.
The second reason is because it is based on a relative weight compared to the standard of Carbon-12 = 12amu. They simple set up the question: How much heavier / lighter is the object compared to carbon-12? Since things are not always a whole number amound heavier than others, we get decimals.
Hydrogen, for example, has 3 isotopes: Hydrogen, Deuterium, and Tritium. Normal Hydrogen has a mass of 1, deuterium a mass of 2, and tritium a mass of 3. The regular hydrogen is the most abundant by far, that is why the mass is only slightly over 1.
The second reason is because it is based on a relative weight compared to the standard of Carbon-12 = 12amu. They simple set up the question: How much heavier / lighter is the object compared to carbon-12? Since things are not always a whole number amound heavier than others, we get decimals.
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Sabrina
Guest
they are not whole #'s because (if you got them from the Periodic Table) they are the average weight of their isotopes (unstable states)
hope i helped : )
hope i helped : )
VictoriaEverglot
New member
They are an average of the masses includeing the isotopes?