Discuss the orbital shapes of the following covalent molecules:
(i) HF (ii) H₂O (iii) NH₃.

(i) Hydrogen fluoride molecule (HF): The electronic configuration of hydrogen is 1s¹. Electronic configuration of Fluorine is 1s² 2s² 2p⁵. Therefore half-filled orbital of hydrogen atom overlaps with the half filled 2p-orbital of fluorine atom to form H – F molecule.

(ii) A water molecule (H₂O): The electronic configuration of hydrogen is 1s¹. Electronic configuration of oxygen 1s² 2s² 2p⁴. Therefore  half-filled orbital of each hydrogen atom overlaps with each of the half-filled 2p–orbitals having electrons in opposite spins of oxygen atom to form H₂O molecule.

(iii) Ammonia molecule (NH₃): The electronic configuration of hydrogen is 1s¹. Electronic configuration of nitrogen is 1s² 2s² 2p³. Therefore the orbital of each hydrogen atom overlaps with each of the three nitrogen orbitals.

half-filled 2p orbitals of nitrogen having electrons in opposite spin to form NH₃molecule.