The Composition of Water

The Composition of Water

  • Water is a compound made up from two different elements: hydrogen and oxygen.
  • Each water molecule, represented as H2O, is composed of two hydrogen atoms and one oxygen atom.
  • Water is a result of covalent bonding, where hydrogen and oxygen share electrons to achieve stable electron configurations.

Covalent Bonding in Water

  • In the water molecule, oxygen atom is at the centre with two hydrogen atoms attached to it.
  • The oxygen atom shares a pair of electrons with each hydrogen atom, forming two covalent bonds.
  • Covalent bonds are strong and require a good deal of energy to break.

Water’s Polar Nature

  • Water molecules are polar, which means they have a slight charge. The oxygen side is negatively charged while the hydrogen side is positively charged.
  • The polarity results from oxygen having a stronger pull or electronegativity on shared electrons compared to hydrogen. This causes electron pairs to be more attracted towards the oxygen atom, resulting in a charge difference.
  • This polar nature gives rise to some significant properties of water, including its ability to dissolve many substances (solvent properties) and its relatively high boiling point compared to other similar sized molecules.

Physical and Chemical Properties

  • Water is liquid at room temperature with a boiling point of 100°C and a freezing point of 0°C.
  • Water exhibits cohesive and adhesive properties due to its polarity and hydrogen bonding. This allows water to stick to itself (cohesion) and to other substances (adhesion).
  • Water can undergo electrolysis, a chemical process where it is broken down into hydrogen and oxygen gas by passing an electric current through it.

Interaction with Other Substances

  • Water can dissolve many substances, earning it the nickname “universal solvent”. This is because its polarity allows it to interact with ionic and other polar compounds.
  • However, water does not dissolve non-polar substances like oil. These compounds are referred to as hydrophobic (water-fearing).
  • Water’s ability to dissolve many substances allows it to carry nutrients and minerals in biological systems and in the environment.