This is because of the existence of isotopes. What's an isotope? It's an element that has a specific number of neutrons. I'll give an example. Carbon has 6 Neutrons, 6 Protons, 6 Electrons.
That's the most common form of Carbon. But 1% of all Carbon is an isotope that has 1 extra Neutron. So it weighs 1 more, also. So this isotope weighs 13 instead of 12. We call it Carbon 13, or 13C.
There's also a 14C and so on....but in far smaller amounts.
So anyhow, since we have 99% Carbon weighing 12 and 1% Carbon weighing 13, what weight do we put on our Periodic Table?
Well, I guess we could put the most common.
But what about Bromine? That has 2 major isotopes. One weighs 79 and the other 81, they are 51% and 49% (very roughly) abundant respectively.
That's almost an exact split...it'd be pretty ridiculous to only put the weight of one.
So instead we say it's weight is 79.9...which is it's weight averaged over all of it's isotopes, with respect to their abundance.
It doesn't seem right to average it on an atom-to-atom basis. But if I'm weighing 2grams of my sample, there are HUGE numbers of molecules there. And the only way I can do an accurate calculation is to know an averaged mass, because my sample WILL contain all of the isotopes.
If I calculate for only 1 isotopic weight, my calculations will be wrong. That's why we average them.
This is because of the existence of isotopes. What's an isotope? It's an element that has a specific number of neutrons. I'll give an example. Carbon has 6 Neutrons, 6 Protons, 6 Electrons.
That's the most common form of Carbon. But 1% of all Carbon is an isotope that has 1 extra Neutron. So it weighs 1 more, also. So this isotope weighs 13 instead of 12. We call it Carbon 13, or 13C.
There's also a 14C and so on....but in far smaller amounts.
So anyhow, since we have 99% Carbon weighing 12 and 1% Carbon weighing 13, what weight do we put on our Periodic Table?
Well, I guess we could put the most common.
But what about Bromine? That has 2 major isotopes. One weighs 79 and the other 81, they are 51% and 49% (very roughly) abundant respectively.
That's almost an exact split...it'd be pretty ridiculous to only put the weight of one.
So instead we say it's weight is 79.9...which is it's weight averaged over all of it's isotopes, with respect to their abundance.
It doesn't seem right to average it on an atom-to-atom basis. But if I'm weighing 2grams of my sample, there are HUGE numbers of molecules there. And the only way I can do an accurate calculation is to know an averaged mass, because my sample WILL contain all of the isotopes.
If I calculate for only 1 isotopic weight, my calculations will be wrong. That's why we average them.
The Atomic Mass of an element is a weighted average because it takes into account the abundance of each isotope of that element. Isotopes are atoms of the same element with different mass numbers due to varying numbers of neutrons. The atomic mass is calculated by multiplying the mass of each isotope by its relative abundance and summing up these values to give an average.
This is because of the existence of isotopes. What's an isotope? It's an element that has a specific number of neutrons. I'll give an example. Carbon has 6 Neutrons, 6 Protons, 6 Electrons.
That's the most common form of Carbon. But 1% of all Carbon is an isotope that has 1 extra Neutron. So it weighs 1 more, also. So this isotope weighs 13 instead of 12. We call it Carbon 13, or 13C.
There's also a 14C and so on....but in far smaller amounts.
So anyhow, since we have 99% Carbon weighing 12 and 1% Carbon weighing 13, what weight do we put on our Periodic Table?
Well, I guess we could put the most common.
But what about Bromine? That has 2 major isotopes. One weighs 79 and the other 81, they are 51% and 49% (very roughly) abundant respectively.
That's almost an exact split...it'd be pretty ridiculous to only put the weight of one.
So instead we say it's weight is 79.9...which is it's weight averaged over all of it's isotopes, with respect to their abundance.
It doesn't seem right to average it on an atom-to-atom basis. But if I'm weighing 2grams of my sample, there are HUGE numbers of molecules there. And the only way I can do an accurate calculation is to know an averaged mass, because my sample WILL contain all of the isotopes.
If I calculate for only 1 isotopic weight, my calculations will be wrong. That's why we average them.
The average atomic mass is a weighted average of the masses of all isotopes of an element, taking into account their abundance. The atomic mass listed on the periodic table is the weighted average of all naturally occurring isotopes of the element. So, they are essentially the same thing, with the average atomic mass being a more specific term.
The atomic mass of an element is the average mass of an element's isotopes, weighted by their natural abundance. It is expressed in atomic mass units (u) and is often close to the mass number of the most abundant isotope of the element.
The atomic mass of an element is the average of its isotopes, weighted by abundance in nature.
Average atomic mass is the weighted average mass of all the isotopes of an element, taking into account their natural abundances. Atomic mass refers to the mass of a single atom of a specific isotope of an element.
it is the weighted average of the masses of an element's isotopes.
The average atomic mass is a weighted average of the masses of all isotopes of an element, taking into account their abundance. The atomic mass listed on the periodic table is the weighted average of all naturally occurring isotopes of the element. So, they are essentially the same thing, with the average atomic mass being a more specific term.
The atomic mass of an element is the average mass of an element's isotopes, weighted by their natural abundance. It is expressed in atomic mass units (u) and is often close to the mass number of the most abundant isotope of the element.
The average atomic mass of an element is the average of the atomic masses of its isotopes (that is a weighted average). You have to take into account the abundance of each isotope when they do your averaging.
The weighted average for all isotopes that occur in nature for an element is its atomic weight listed on the Periodic Table of the elements.
The weighted average of the atomic masses of an element's naturally occurring isotopes is called the atomic mass. This value takes into account the abundance of each isotope in nature when calculating the overall average atomic mass of the element.
The atomic mass of an element is the average of its isotopes, weighted by abundance in nature.
The atomic mass of an element is the average of its isotopes, weighted by abundance in nature.
Average atomic mass is the weighted average mass of all the isotopes of an element, taking into account their natural abundances. Atomic mass refers to the mass of a single atom of a specific isotope of an element.
The atomic mass of an element is the weighted average of masses of the isotopes of the element, weighted in proportion to their abundance.
it is the weighted average of the masses of an element's isotopes.
What is weighted average atomic number
Atomic weight or atomic mass used in stoichiometric calculations.