I was wondering if someone could perhaps EXPLAIN how to solve this problem. =]
Assume that element Uus is synthesized and that it has the following isotopes:
284Uus (283.4 amu) 34.60%
285Uus (284.7 amu) 21.20%
288 Uus (287.8 amu) 44.20%
What is the value of the average atomic mass for Uus that would be listed on the periodic table? [please use significant figures]
I don't even know how to begin this problem. x] Thanks to anyone that can help. :]
2006-07-16 07:48:10 · 11 answers · asked by sooper mouse! 2 in Science & Mathematics ➔ Chemistry
The atomic number of an element listed in the periodic table is the average of all the atomic numbers of all the isotopes of that element. The average of all the atomic numbers is the sum of the fraction of each isotope times their masses. Therefore, from the information given, the average is .346*283.4 + .212*284.7 + .442*287.8 = 285.6amu
2006-07-16 08:28:05 · answer #1 · answered by prune 3 · 0⤊ 0⤋
The mass in the periodic table is an average of the mass of all isotopes but considering their relative abundance.
For example, imagine you have 100 atoms of an element X that have 2 isotopes. Mass of isotope Nº1 is 50 uma and mass of isotope Nº2 is 60 uma. If you have 40 atoms of isotope N1 and 60 of isotope N2, the average mass will be:
[40x50 (mass of 40 atoms of N1) + 60x60 (mass of 40 atoms of N2)] / 100 (total number of atoms)
So, if this problem you have to add the mass of each isotope multiplied by they relative abundance (%) and then divide by 100.
2006-07-16 08:04:07 · answer #2 · answered by Fede 4 · 0⤊ 0⤋
Simple!
1) multiply the mass of each isotope by the decimal (not %)
ex: 283.4 amu X .3460 = ?
2) after multiplying all three isotope and getting the answers you just add all three answers together. Looks to me like you will need to keep 4 sig figs in your answer.
2006-07-16 10:09:02 · answer #3 · answered by physandchemteach 7 · 0⤊ 0⤋
Let's say you have 100 teenages and you have to find their average weight.
Thirty of them are cheerleaders, they weigh about 105 lbs. each. Forty of them are big football players, they weigh about 250 each. Ten are 98-lb weaklings, and the other 20 are average teens that weigh 120 apiece.
What is the average weight for each person?
First you figure out the total weight, which is 105x30 + 250x40 + 98x10 + 120x20. Then you divide that total poundage by 100 to average the total weight out over the whole population.
Same principle for you, but you have funnier-looking numbers. It's an easy problem, just seems hard. Good luck!
2006-07-16 07:59:15 · answer #4 · answered by Trips 3 · 0⤊ 0⤋
i'm not exactly sure but try multiplying the decimal value of the percentage and multiply it by the mg of Uus for each isotope and add them up.
2006-07-16 07:52:47 · answer #5 · answered by Jwalker 1 · 0⤊ 0⤋
multiple the mass of each isotope by their respective percent and then add the total of the three and that will give you the average atomic mass.
2006-07-16 07:51:54 · answer #6 · answered by larry j 3 · 0⤊ 0⤋
284 Uus = 98.3 atomic mass
285 Uus = 60.42 atomic mass
288 Uus = 127.3 atomic mass
What I did was divide the % by .100 then multiply Uus to get atomic mass. I totally forget my chemistry. Please check your sources.
2006-07-16 07:58:29 · answer #7 · answered by Anonymous · 0⤊ 0⤋
just multiply the atomic mass by the percentage of the isotope and then add them together. thats it!
2006-07-16 10:49:04 · answer #8 · answered by The Frontrunner 5 · 0⤊ 0⤋
no, in the world of chemistry, you deal with number of moles as the number of units. so you write out the equation and calculate everything in terms of moles. :)
2016-03-27 07:50:35 · answer #9 · answered by ? 4 · 0⤊ 0⤋
i feel ur pain
2006-07-16 07:53:33 · answer #10 · answered by shake 1 · 0⤊ 0⤋