Copper has two naturally occurring isotopes. Cu−63 has a mass of 62.939 amu and relative abundance of 69.17%.

Use the atomic weight of copper to determine the mass of the other copper isotope

Question

Copper has two naturally occurring isotopes. Cu−63 has a mass of 62.939 amu and relative abundance of 69.17%.

Use the atomic weight of copper to determine the mass of the other copper isotope

mathstudent55 · Answer

The atomic mass of an element (given in the periodic table) is the average of the atomic masses of its isotopes. It's not just a simple average, it's a weighted average.

mathstudent55 · Answer

From the periodic table, the atomic mass of copper is 63.546 amu.

The problem states that there are only two isotopes of copper.
One isotope accounts for 69.17% of the copper and has an atomic mass of 62.939 amu.
The other isotope has an unknown atomic mass (let's cal it x) and accounts for the remainder of the copper. The remainder is 100% - 69.17% = 30.83%

This means that by calculating a weighted average of the two isotopes, you have to get the atiomic mass that is listed on the periodic table.

69.17% (62.939 amu) + 30.83% (x) = 63.546 amu

0.6917 * 62.939 amu + 0.3083x = 63.546 amu

mathstudent55 · Answer

No. You need to find x in the equation. 63.546 amu is the average atomic mass of all copper.

Solve this equation for x:

0.6917 * 62.939 + 0.3083x = 63.546

toxicsugar22 · Answer

is it 4320.77463

mathstudent55 · Answer

Not even close.
Where do you get these guesses from?

mathstudent55 · Answer

Since you are looking of the atomic mass of an isotope of copper, it must be close the the atomic mass of the given isotope and of the atomic mass given in the periodic table. The number has to be close to 63.546 and 62.939.

mathstudent55 · Answer

No.
Instead of guessing, try solving the equation I gave you.

mathstudent55 · Answer

Solve this equation for x:

0.6917 * 62.939 + 0.3083x = 63.546

Do it one step at a time.
What is 0.6917 * 62.939?

toxicsugar22 · Answer

43.5349063

mathstudent55 · Answer

Good.

43.534906 + 0.3083x = 63.546

Now subtract 63.546 - 43.534906

toxicsugar22 · Answer

20.0110937

mathstudent55 · Answer

Good.
Now you have 
0.3083x = 20.0110937

Now divide 20.0110937 by 0.3083 to find x.
That is your answer.

toxicsugar22 · Answer

64.9078615

mathstudent55 · Answer

$ \LARGE \color{red}{B} \color{blue}{I} \color{green}{N} \color{brown}{G} \color{purple}{O} !!!!!!!!!$

mathstudent55 · Answer

That is the answer.

toxicsugar22 · Answer

can you help with oone more

toxicsugar22 · Answer

Enter the appropriate symbol for an isotope of phosphorus-32 corresponding to the isotope notation

toxicsugar22 · Answer

ISNT IT $$\frac{ 30 }{ 15 }P$$