Final answer:
In a water molecule, oxygen has the greatest electronegativity, leading to the polar nature of water and its ability to form hydrogen bonds.
Step-by-step explanation:
Because oxygen has an electronegativity of 3.44 compared to hydrogen's 2.20, it attracts the shared electrons in the molecule more strongly than the hydrogen atoms do. Consequently, the shared electrons spend more time near the oxygen atom, resulting in a higher electron density around it and making the oxygen end of the water molecule slightly negative. This imbalance in electron density is significant, as it contributes to the molecular polarity of water, where hydrogen atoms acquire a partial positive charge and oxygen atoms a partial negative charge. The high electronegativity of oxygen relative to hydrogen in water molecules leads to its well-known polar properties and its ability to form hydrogen bonds.