Question

Element A belongs to group 15 and period 2 of the Periodic Table.
(a) Identify the element A.
(b) Write the formula of the compound formed when element A combines with hydrogen.
(c) Draw the dot (●) and cross (×) structure of the compound formed in (b) above.

Hint:

The presence of the lone pair on the nitrogen atom is what gives ammonia its basic properties and its ability to form coordinate bonds!

Answer 1

(a) Identification: An element in Period 2 has 2 shells. Group 15 indicates 5 valence electrons. The element is Nitrogen (N) (Atomic number 7, configuration 2, 5).

(b) Formula: Nitrogen requires 3 electrons to complete its octet, and Hydrogen has 1 electron. The compound formed is Ammonia (NH_3).

(c) Electron Dot Structure: The Nitrogen atom (center) shares three of its five valence electrons with three Hydrogen atoms, leaving one lone pair.