The shape of a molecule of water is _______?

Step 1: Analyze the question We need the shape of the water molecule (H₂O).

Step 2: The concept (VSEPR theory) The shape of a molecule depends on the number of bonding pairs and lone pairs of electrons around the central atom. Electron pairs repel each other and arrange themselves as far apart as possible.

Step 3: Apply it to water

• Central atom: Oxygen (6 valence electrons)
• Two of these electrons form bonds with two hydrogen atoms (2 bond pairs)
• The remaining 4 electrons form 2 lone pairs
• Total electron pairs = 4, so the electron arrangement is tetrahedral
• The two lone pairs repel the bond pairs more strongly than bond pairs repel each other. This squeezes the H–O–H angle to about 104.5° instead of 109.5°.
• Only the atoms determine the molecular shape, so the molecule is bent (V-shaped or angular). In WASSCE terms, this is called non-linear.

Step 4: Check the options

• A. Non-linear: correct, since the molecule is bent
• B. Octahedral: this needs 6 electron pairs, as in SF₆
• C. Pyramidal: this has 3 bond pairs and 1 lone pair, as in NH₃
• D. Tetrahedral: this has 4 bond pairs and no lone pairs, as in CH₄. The electron pairs of water are arranged tetrahedrally, but the molecule's shape is not tetrahedral.

Answer: A. Non-linear

Exam tip: Remember the pattern by counting lone pairs on the central atom:

• CH₄: 0 lone pairs, tetrahedral
• NH₃: 1 lone pair, pyramidal
• H₂O: 2 lone pairs, bent or non-linear
• CO₂: 0 lone pairs and 2 bond pairs, linear