write isotpoic symbols of the form X-A (for example, C-13) for each of the following isotopes.

**Do I add the number of protons and neutrons together to get the answer?
The symbol is easy to figure out.**

a) the iodine isotope with 74 neutrons

B) the phosphororus isotope with 16 neutrons

C) the uraanium isotope with 234 neutrons

D) the argon isotope with 22 neutrons

Yes. The symbol is the atomic number as well as the number of protons.
# protons + # neutrons = mass number.
I-(53+74)= I-127

I wasn't sure about this one. I thought the number that I got was too big. But you showed me I did it right thanks!

Ha! I forgot to change my brothers name from the box.

But yeah that was melinda. Thanks!

I wonder if the U one is correct. There is a U-234 but there is no U-(92+234)=U-326.

I - 127

No problem! Let's correct the answers:

a) The iodine isotope with 74 neutrons:
Iodine is element number 53 and has a mass number of 127. So the isotopic symbol is: I-127.

b) The phosphorus isotope with 16 neutrons:
Phosphorus is element number 15 and has a mass number of 31. So the isotopic symbol is: P-31.

c) The uranium isotope with 234 neutrons:
Uranium is element number 92, but there is no isotope with 234 neutrons. The closest one is Uranium-238 (U-238) which has 238 - 92 = 146 neutrons.

d) The argon isotope with 22 neutrons:
Argon is element number 18 and has a mass number of 40. So the isotopic symbol is: Ar-40.

No problem! Let me help you figure it out. The atomic number of uranium is 92 since it is found in periodic table. The atomic number represents the number of protons in an atom's nucleus. Now, to figure out the mass number of the uranium isotope with 234 neutrons, you would add the number of protons (92) and the number of neutrons (234).

So, the isotopic symbol for this uranium isotope would be U-326. It seems like you made a calculation mistake earlier. Remember, the isotopic symbol consists of the element symbol (U for uranium), followed by a hyphen, and then the mass number (number of protons + number of neutrons).