An atom of element x has one more shell of electrons than an atom of beryllium, but it has one less valence electron than beryllium. which is element x? a. sodium b. boron c. magnesium d. lithium

Element X is Na, sodium.

Be is in Row 2, Group 2 and has two valence electrons.

The element with one more shell of valence electrons is Mg, magnesium in Row 3, Group 2.

If the element has one less electron than Be, it must be in Row 3, Group 1: Na, sodium.

it should be all of them because it asks if you included all of those in your answer

explanation: