the table compares the number of electrons in two unknown neutral atoms.
comparison of electrons
atom number of electrons
a 9
d 11
use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? (5 points)
both are unreactive.
both are highly reactive.
a is unreactive and d is reactive.
a is reactive and d is unreactive.

Option B is the Answer.

Both are highly reactive.

Explanation:

For a neutral atom,

Atomic number = number of electrons = number of protons.

We can identify the element from its atomic number

It says 9 and 11 are the atomic number. By looking at the periodic table we know the elements are Fluorine and sodium.

Na has 2 electron in the first shell and 8 in the second and 1 in the outer shell

F has 2 electron in the first shell and 7 in the outer shell.

Atoms with less than 8 electrons in the outer shell are not stable. In order to attain stability atom either loses or gains or shares its electron and gets 8 electron in its outer shell to become more reactive.

Sodium easily loses its outer shell electron and becomes reactive

Na (2,8,1) becomes (2, 8)

Fluorine gains easily an electron and becomes reactive.  

F (2, 7) becomes (2, 8)

Having 8 electrons in its outershell electron makes an atom more stable.