Question

element #72 hafnium has an atomic mass of 178. how many neutrons are there in hafnium? 72 hf hafnium 178.49 106 72 178 250

Explanation:

Step1: Recall atomic number concept

The atomic number of Hafnium is 72, which means the number of protons is 72.

Step2: Use neutron - proton relationship

The formula for atomic mass ($A$) is $A =$ number of protons ($p$)+ number of neutrons ($n$). Given $A = 178$ and $p=72$, we can find $n$ as $n=A - p$.

Step3: Calculate number of neutrons

$n=178 - 72=106$.

Answer:

106