Question

question 11 atomic structure and the periodic table
how many atoms of lithium - 6 will contain 21 neutrons?
select one
5
9
3
7

Explanation:

Step1: Determine neutrons per atom

Lithium - 6 has mass number \(A = 6\). For lithium, atomic number \(Z=3\) (from periodic table). Using \(A=Z + N\), we find \(N=A - Z=6 - 3 = 3\) neutrons per atom.

Step2: Calculate number of atoms

If total neutrons \(N_{total}=21\), then number of atoms \(n=\frac{N_{total}}{N}=\frac{21}{3}\)

Answer:

7