Question

An element has three naturally occurring isotopes. Use the information below to calculate the weighted average atomic mass of the element, showing both the setup and the final answer for the calculation.

Isotope

Atomic Mass

Percent Abundance

X

1.01 u

99.984%

Y

2.01 u

0.014%

Z

3.02 u

0.002%

Answer 1

@jim_thompson5910 hello! would u mind helping me?

Answer 2

Are you familiar with weighted averages?

Answer 3

would it be 1.01 u

Answer 4

no

Answer 5

The idea is to multiply each mass with it's percentage divided by 100

then you add up those products

Answer 6

For isotope X: 1.01*99.984/100 = 1.0098384

For isotope Y: 2.01*0.014/100 = 0.0002814

I'll let you do isotope Z

Answer 7

Okay so 3.02(0.002/100)

Answer 8

yes, giving you what

Answer 9

0.0000604

Answer 10

Add that to 1.0098384 and 0.0002814 to get


1.0098384 + 0.0002814 + 0.0000604 = ???

Answer 11

0.0003418

Answer 12

1.0098384 + 0.0002814 + 0.0000604 = 1.0101802

Answer 13

made a typo earlier before, but 1.0101802 is the answer

Answer 14

Oops I knew I added that up wrong

Answer 15

thank you! I understand now

Answer 16

yw

Answer 17

Is it C? The average atomic mass recorded on the periodic table for krypton is 83.80 u. This indicates that the most abundant isotope of krypton is

krypton-82.

krypton-83.

krypton-84.

krypton-85.

Answer 18

I'm not sure. I'm not a chem expert.

Answer 19

but if the number 83.8 refers to the numbers after the "kyrpton" then 83.8 is close to 84, so C looks good

Answer 20

Okay, thats what I figured. thanks! No one on chemistry is replying to questions :(

Answer 21

it's probably because chem is a one-time class that people forget when they pass (i know I've forgotten a lot of it and I only had to take one class)

compare this to math where everyone has to take it (at least 2 years of it when I went to HS) and math is usually more universal (compared to chem)

Answer 22

Oh okay. Its too bad because chemistry is not a strong subject of mine. I like math more which says something...Lol!

Answer 23

that's great, you'll go really far with that love of math

Answer 24

Do you think you could help me with this one....Which of the following sets represents a pair of isotopes?

14C and 14N

Br and Br2

9B and 11B

16O and 16O2-

Answer 25

hmm

Answer 26

isotopes are from the same element I think

Answer 27

so that would eliminate A

Answer 28

I was thinking c

Answer 29

maybe, B looks like it's just the same element (just in different forms), so does D

Answer 30

Alrighty! :)

Answer 31

The atomic and mass numbers for four different atoms are given below. Which two are isotopes of the same element?
Atom A has an Atomic Number of 100 and a Mass number of 258

Atom B has an Atomic Number of 101 and a Mass number of 258

Atom C has an Atomic Number of 102 and a Mass number of 260

Atom D has an Atomic Number of 102 and a Mass number of 259

a.A and B
b.B and C
c.B and D
d.C and D

Answer 32

D?

Answer 33

C and D sounds good, so it's choice D (lol very confusing choice of letters)