Water is a chemical substance composed of two hydrogen atoms bonded to one oxygen atom, giving it the chemical formula H₂O. It is a colorless, tasteless, and odorless liquid at room temperature and is essential for all known forms of life.
Water exists in three states: liquid, solid (ice), and gas (water vapor or steam). Its unique properties include:
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Polarity: Water molecules have a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom, making water a polar molecule. This polarity allows it to form hydrogen bonds, which contribute to its high boiling point and specific heat capacity.
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Solvent Properties: Water is often referred to as the "universal solvent" because it can dissolve many substances, which is crucial for biological and chemical processes.
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High Specific Heat and Heat of Vaporization: Water can absorb and store large amounts of heat, which helps regulate temperatures in the environment and in living organisms.
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Density: Water is most dense at 4°C (39°F); ice floats on liquid water because it is less dense in its solid form.
Water is vital for agriculture, industry, and domestic use, and it plays a key role in the Earth's weather systems and hydrological cycle.