Question

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 element is element X?

sodium (Na)
boron (B)
magnesium (Mg)
lithium (Li)

Answer 1

Sodium has three shells of electrons instead of two and has one electron in its valence shell. Beryllium has two in its valence shell.

Answer 2

Correct answer choice is :

A) sodium (Na)

Step-by-step explanation:

It's a light element, reactive and with a low melting point, with a corresponding density of 0,97 at 20ºC. From the business point of view, sodium is the most significant of all the alkali elements. Sodium acts immediately with water, and also with snow and ice, to create sodium hydroxide and hydrogen.