boron obtain from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11...?

Question

with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table). Which isotope of boron is more abundant, boron-10 or boron-11?

Could you please show the steps in your results. (TIA)

Answer 1

The atomic mass given on the periodic table(with the decimal point) is a weighted average of all the isotopes, weighted by their abundance.
If the mass given is 10.8, we usually round it to the nearest whole number.
Since 11 is closest to the mass 11.009, that isotope is the most abundant.

Answer 2

If the fraction of 10B is y, and the fraction of 11B is (1 - y), then the observed atomic mass is equal to y x 10.013 + (1 - y) x 11.009. This is because the observed atomic mass of an element is just the weighted average of the atomic masses of the different isotopes. To solve your problem, all you need to do is see whether y is more than or less than 1/2.

Actually, this question is back to front. These days, the way and atomic masses are determined is by measuring the masses, and the relative abundances, of all the isotopes in a mass spectrometer. So we actually calculate the atomic mass of the element boron using the information that you are being asked to find out.

Answer 3

This is easy. Since the average atomic mass of 10.81 is much closer to the mass of the heavier isotope (11.009), that isotope must be more abundant. (If the two isotopes had been present in equal quantities, the average mass would have been halfway between, or 10.511.)

Answer 4

Boron will always have 5 protons....to get the neutrons, all you have to do is subtract the protons from the number of element (like boron 11). So 11-5=6. Boron has 5 protons and 6 neutrons. Hope ti helped!!! =]

Answer 5

10.81= (10.003)x + 11.009(1-x)
10.81 = 10.013x + 11.009 - 11.009x
10.81-11.009 = 10.013 x - 11.009x
-0.199 = -0.996x
-0.199/-0.996 = x
x = 0.2
20% is Boron 10
80 % is Boron 11

To check multiply 10.013 x .2 and add it to 11.009 x .8