Question

The electron dot diagram shows the arrangement of dots without identifying the element.

? with 2 dots above and 1 dot each right, below, left.

Which element’s symbol could replace the question mark in the diagram?

boron (B)
neon (Ne)
rubidium (Rb)
arsenic (As)

Answer 1

The diagram shows 5 valence electrons (a pair + three singles). That corresponds to a group 15 element. Of the choices, only arsenic (As) has 5 valence electrons — so As is correct.