Question

Use the periodic table to complete the activity.

The periodic table of elements shows element groups, periods, and element properties.

In 3–5 sentences, predict how phosphorus and chlorine would bond. Explain why they would bond that way.

Answer 1

Phosphorus (group 15) has five valence electrons and chlorine (group 17) has seven, so they are both nonmetals and will bond by sharing electrons (covalent bonding) rather than by forming an ionic salt. Phosphorus commonly shares three electrons to make PCl3 so it completes an octet, while each chlorine shares one electron to complete its octet. Because phosphorus is in the third period it can also expand its valence shell and form PCl5 in suitable conditions. The bonds are polar covalent (Cl is more electronegative than P), so the shared electrons sit closer to the chlorine atoms.