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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.
What else can I help you with?
The atomic weight of Br is the of the atomic weights of Cl and l?
The atomic weight of Br (Bromine) is the sum of the atomic weights of Cl (Chlorine) and I (Iodine). This is because bromine falls between chlorine and iodine in the periodic table, thus its atomic weight is approximately the average of the atomic weights of chlorine and iodine.
Who was The first attempt at publishing a list of relative atomic masses?
John Dalton tried to work out the relative masses of atoms; but his calculations were wrong, although the principle was correct. He was, however, the first to establish a table of atomic masses with hydrogen, the lightest atom, as the standard.
Can you find any cases in the first 90 elements where consecutive elements do not have increasing atomic weights?
Yes, in the first 90 elements of the periodic table, there are a few instances where consecutive elements do not have increasing atomic weights. For example, the atomic weight of Cobalt (Co) is 58.93, which is less than the atomic weight of Nickel (Ni) at 58.69. Another example is the atomic weight of Tellurium (Te) at 127.6, which is less than the atomic weight of Iodine (I) at 126.90447. These anomalies occur due to variations in the atomic mass of isotopes and their relative abundances.
What is the relative formula mass of copper?
The relative atomic mass of copper is approximately 63.55. To calculate the relative formula mass of copper, you sum the atomic masses of its atoms, which in this case would just be the atomic mass of copper. Therefore, the relative formula mass of copper would be 63.55.
What is the atomic weight of the element Tantalum?
The atomic weight of Tantalum is approximately 180.947.
What is often used in place of atomic weights?
Relative atomic masses are often used in place of atomic weights. They represent the weighted average of the masses of the isotopes of an element relative to the mass of a carbon-12 atom.
To which element are all atomic weights relative?
That would be Carbon (C). Which has a designated mass of 12.
Base weight a system of comparing atomic weights to carbon is it true or false?
True. The unit for the atomic weights of chemical elements is the relative atomic mass unit (1/12 from the atomic mass of the isotope 12C). Note that atomic weights is used for elements and atomic mass for isotopes.
What elements did John Dalton discover the atomic weights of?
John Dalton determined the atomic weights of several elements, including hydrogen, oxygen, carbon, nitrogen, and sulfur, among others. He used hydrogen as the reference point with an atomic weight of 1, assigning relative weights to other elements based on their combinations with hydrogen. Dalton's work laid the foundation for the modern understanding of atomic theory and the relative weights of elements. His findings were crucial in advancing the field of chemistry in the early 19th century.
Why do atomic weights are in fraction?
Because atomic weights must be measured in fractions.
On what were the original atomic weights based?
The original atomic weights were based on the mass of hydrogen.
Why are atomic weights realitive weights?
Actually weights are too small and are hard to work with.
How relative atomic mass is related to gram?
relative Atomic Mass
How the relative atomic mass is related to gram?
relative atomic mass
The atomic weight of Br is the of the atomic weights of Cl and l?
The atomic weight of Br (Bromine) is the sum of the atomic weights of Cl (Chlorine) and I (Iodine). This is because bromine falls between chlorine and iodine in the periodic table, thus its atomic weight is approximately the average of the atomic weights of chlorine and iodine.
What is the relative atomic mass of potassium?
the relative atomic mass for the element potassium is 39.0983
How is atomic mass caluclated?
It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.
