What Is Water Made Up Of?

Composition of Water

• Water is chemically known as dihydrogen monoxide (H2O) with two hydrogen atoms and one oxygen atom.
• The chemical formula for water is derived from its chemical structure.
• Other names for water include oxidane, hydrogen hydroxide (H-OH), dihydrogen oxide, hydric acid, hydrohydroxic acid, and its CAS registry number is 7732-18-5.

Structure of Water Molecule

• Each hydrogen atom shares a single electron pair with the oxygen atom, forming a covalent bond.
• The oxygen atom has two free electron pairs that repel each other, causing the bonding pair (H-O) to push closer to each other, resulting in a bond angle of 104.5°.
• Oxygen has a higher electronegativity than hydrogen, resulting in unequal distribution of electrons and making water a polar compound.

Physical Properties of Water

• Water has a high cohesion due to the formation of hydrogen bonds between water molecules, resulting in strong intermolecular forces.
• Hydrogen bonds contribute to water's high boiling point and surface tension.
• Viscosity is the measure of fluid friction relative to its internal resistance to flow, and water has a low viscosity.

Heat Capacity of Water

• The heat capacity of water is 4180 J/kg°C, meaning it requires a significant amount of energy to increase the temperature of water by 1 degree.
• This property is related to the hydrogen bonding, requiring energy to break these bonds.

Density of Water

• Water can exist in all three phases: liquid, solid, and gas.
• The density of water decreases as the temperature decreases, and it is solid at 0°C with a lower density than liquid water.

Polarity and Solvent Properties

• Water is considered a universal solvent due to its polarity, allowing it to dissolve a wide range of substances.
• Water's polarity is attributed to its unequal distribution of electrons, resulting in a partially negative charge on the oxygen atom and a partially positive charge on the hydrogen atoms.

Chemical Properties of Water

• Water is amphoteric, meaning it can act as both an acid and a base.
• Water can act as an oxidizing agent in oxidation-reduction reactions and as a reducing agent in other reactions.
• Hydrolysis is a reaction where chemical bonds are cleaved when water is added.

Significance of Water's Unique Properties

• The unique properties of water make life on earth and within biological specimens possible.
• Water's temperature regulation in the human body is crucial for maintaining a stable body temperature.
• The properties of water help understand the water cycle, including capillary action in plants and the floating of ice on water.