describing isotopes\nwhat is the mass number of the isotope lithium - 7?\nlithium has 3 protons. how many…
describing isotopes\nwhat is the mass number of the isotope lithium - 7?\nlithium has 3 protons. how many neutrons are in the isotope lithium - 8?
Answer
Explanation:
Step1: Recall mass - number notation
The notation lithium - 7 indicates that the mass number is 7.
Step2: Recall mass - number formula
The mass number (A) is the sum of protons (p) and neutrons (n), i.e., $A=p + n$. For lithium - 8, $A = 8$ and $p=3$. We solve for $n$: $n=A - p$.
Step3: Calculate number of neutrons
Substitute $A = 8$ and $p = 3$ into the formula $n=A - p$. So $n=8 - 3=5$.
Answer:
7 5