Water: Definition, Structure, & Examples

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Water Definition

  • Water is a chemical compound with the molecular formula H2O that is a clear, colorless, odorless, and tasteless liquid that also exists in gaseous (water vapour) and solid (ice) forms.
  • A substance found in an aqueous solution, such as ammonia water or wastewater.
  • A body of water, such as a sea, a river, or a lake, as well as water produced naturally, such as mineral water.
  • Amniotic fluid, as in a pregnant woman’s water breaks.

What is Water?

Water (Chemical Formula: H2O) is a chemical compound made up of two hydrogen atoms joined by a covalent connection to the central oxygen atom. This arrangement results in a polar molecule. Because a water molecule is polarised, its electropositive hydrogen is electrostatically attracted to the neighbouring water molecule’s electronegative oxygen atom.

The hydrogen bond is the electrical dipole-dipole interaction between water molecules. A translucent, colourless, odourless, and tasteless liquid is formed by transitory hydrogen bonding between water molecules.

Water may be found in a variety of states, including liquid, gas (as water vapour), and solid (as ice). Water’s unique features, such as its high boiling point (100 °C), high surface tension, specific heat, and heat of vaporisation, are due to hydrogen bonding between water molecules.

Water Properties

Because of its chemical and physical characteristics, water is known as the universal solvent. Carbon dioxide, oxygen, mineral substances, and salts are the other primary inorganic compounds of biological significance. The following are some of water’s unique characteristics. Under normal circumstances, water is a liquid.

At room temperature and pressure, it is a tasteless and nearly odourless liquid. It’s also translucent, allowing aquatic plants to thrive by allowing sunlight to pass through. When water freezes, it is referred to as ice. At temperatures below 4 °C, water expands (rather than shrinks). As a result, when it freezes, it loses density.

The solidified water (ice) floats above the surface as a result of this. As a result, species may still survive beneath the ice surface of oceans and seas. Water vapour is the gaseous form of water that has a high heat of vaporisation. Convection transports water vapour into the atmosphere on Earth. Clouds are formed as a result of this. Rainwater is provided by the clouds to living creatures.

Water is a Polar Molecule

A water molecule is made up of one oxygen atom in the centre and two smaller hydrogen atoms linked to it. A covalent connection connects each of these hydrogen atoms to the oxygen. As a result, a partially positive and partially negative pole is formed (thus, making water a polar molecule).

It creates a temporary hydrogen connection with a neighbouring water molecule in addition to the covalent link. A hydrogen bond is what holds water molecules together. The oxygen in water has a small negative charge, whereas the hydrogen molecules have a slight positive charge, making it a polar molecule.

Because of its polarity, it is a great solvent for a wide range of compounds. Cations are attracted to slightly negative oxygen, while anions are attracted to slightly positive hydrogen. As a result, water can dissociate and ionise molecules.

Water Has High Surface Tension

The surface tension of water is rather high. This indicates that water molecules have a stronger attraction to one another (due to cohesion) than air molecules (due to adhesion). Water has a low viscosity, which implies it is easy to flow through. By reducing water loss from the leaf stomata, these characteristics are vital to plants. Insects that can walk on water are helped by the water’s high surface tension.

Water: Adhesion Properties

Water has a high level of stickiness. Water, as a result, has the capacity to capillary action, or the propensity to flow up a small tube against gravity, which vascular plants, such as trees, rely on.

Water: Specific Heat Properties

The second largest specific heat capacity is that of water (after ammonia). The quantity of energy (in calories or joules) necessary to raise the temperature of one gramme of a pure material by one degree Celsius is referred to as specific heat. The high specific heat of water aids in maintaining a suitable temperature on Earth for life. For example, during the day, the ocean collects a large amount of solar energy before dissipating it into the atmosphere at night.

Biological Importance of Water

Water is one of the most important elements in existence. Water dissolves biomolecules (such as DNA, proteins, and polysaccharides), gases, vitamins, and other substances. Water might be used as a vehicle to deliver these chemicals to different regions of the body. It’s also a key reactant in a number of biological reactions.

Water is a necessary component of photosynthesis in plants. Water molecules may establish temporary hydrogen bonds amongst themselves because they are polar, which aids in the creation of biomolecular structures like DNA and proteins. Because of its polarity, water is able to interact with ions and other polar molecules.

Water aids in the dissociation of chemicals into ions. As a result, it aids in the regulation of pH levels. Hydrophilic molecules or compounds are those that are easily soluble in water. Hydrophobic substances, on the other hand, are those that are not easily soluble in water. They’re nonpolar, which means they don’t dissolve easily in water.

Water’s interactions with polar and nonpolar molecules are critical to the lipid-bilayer plasma membrane’s function and structure. The most abundant molecule inside a cell is water, which makes up 70% or more of the entire cell mass. The cytosol of the cell includes water (along with ions, solutes, and other compounds).

Body water refers to the amount of water in a person’s body. It may be found in a variety of tissues, including bones, muscles, adipose tissue, blood, and almost everywhere else. Water accounts for roughly 50 to 60 percent of the average adult human body.A newborn infant’s body has a larger amount of water (as much as 93 percent of the bodyweight). Body water is found in different biological fluids, such as extracellular fluid and intracellular fluid, in humans (and animals).

The extracellular fluid, which makes up 1/3 of the body’s water, is found outside of cells in the body. Intracellular fluids are those that are present inside cells. They make up roughly two-thirds of the body’s water.

On Earth, there is plenty of water. It might be solid, liquid, or gaseous. Water covers around 70% of the Earth’s surface. Water bodies on Earth provide significant habitat for aquatic organisms as well as a supply of water for terrestrial life. Marine water, freshwater, and brackish water are the three main types of aquatic ecosystems.

Apart from being a chemical compound having the molecular formula H2O, the word can also refer to a body of water such as the sea, rivers, and lakes, as well as naturally occurring water such as mineral water. It can also refer to a material in an aqueous solution, such as ammonia water or wastewater. It’s also a slang word for amniotic fluid leaking, which occurs before or during childbirth, but before the rupture of the amnion.

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