Question

The table compares the number of electrons in two unknown neutral atoms.

Answer 1

Answer:

Both are highly reactive.

Explanation:

A has 1 valence electron D has 3

A is sodium D is aluminum

Answer 2

Answer:

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 $Na^+$ (2, 8)

Fluorine gains easily an electron and becomes reactive.  

F (2, 7) becomes $F^-$ (2, 8)

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