Question

If you have an isotope of the element carbon (C) that has the mass number of 14, what other information would help you determine the number of neutrons?

A)atomic mass
B)atomic number
C)number of electrons
D)number of isotopes

Answer 1

B) atomic number

Step-by-step explanation:

- The atomic number (Z) of an element corresponds to the number of protons (p) in its nucleus

- The mass number (A) of an element corresponds to the number of protons (p) + neutrons (n) in the nucleus

We can summarize these two definitions as follows:

Z = p

A = p + n

For the isotope of carbon, we know that the mass number is 14:

A = p + n = 14

Therefore, in order to determine the number of neutrons, we also have to know the atomic number Z, so the number of protons.

In reality, the atomic number of carbon is 6, so Z=6 and we can calculate the number of neutrons in this isotope:

n = A - p = 14 - 6 = 8