Question

what relationship exists between the mass number of an element and the isotopes of that element

Answer 1

Well if you think about the mass of the atom there is a kind of relationship:
The mass of the atom is determined by how mutch the isotopes weighs and the relative frequency of appearance.
So if we for an example look at carbon, there are 2 natural isotopes:
\[m \left(\begin{matrix}12 \\ 6\end{matrix}C\right)=12,00000000 u\]
\[m \left(\begin{matrix}13 \\ 6\end{matrix}C\right)=13,00335483 u \]
the two carbon isotopes occurs with the relative frequencies of 98.89% and 1.11% so the calculation is going to look like this:
\[m(C) = 0,9889 . 12,00000000 u + 0,0111 . 13,00335483 u = 12,011 u\]
This is precisely the value of the atomic mass of naturally occurring carbon.

Answer 2

that dot between the procent and the mass is a multiplication sign :P

Answer 3

You are familiar with isotopes right?

Answer 4

"Give the symbol and number of neutrons in one atom of:
(to get "mass number", you must round the "atomic mass" to the nearest whole number) Show your calculations." and we do it for barium, bismuth and carbon.

Answer 5

and others lol

Answer 6

Some notation first:
\[_{Z}^{A}E\]
Here is:
Z the number of protons.
A the nukleon-number/nucleus-number (the number of both protons and nutrons)
E the shorten of the atom name we are talking about.

Out from the we may be able to make the following equation to determine the number of neutrons (N):
\[A=N+Z <-> N=A-Z\]

We asume that the atom found is in then form with the highest relative frequency of appearance and are then able to do the following:
m(E)=m(N) + m(Z) + m(electron)
but becuase m(electron)<< m(N) and m(e)<< m(Z) and we set m(N) and m(Z) =1 we can rewrite to the following:
m(E)=m(N) + m(Z) = A

Answer 7

nevermind! my friends in the class before me, said that what she put was incorrect so we cant do this one :P

Answer 8

Lets see how it works:
\[_{4}^{9}B\]
\[N=9-4=5\]

\[_{83}^{209}Bi\]
\[N=209-83=126\]

\[_{6}^{12}C\]
\[N=12-6=6\]

Answer 9

Damn shame becuase it is damn easy :P

Answer 10

lol xD