Inorganic Ions

Inorganic Ions: An Overview

  • Inorganic ions are atoms or molecules that carry an electrical charge, either negative (anions) or positive (cations).
  • They play vital roles in various biological functions, such as cell signalling, pH buffering, and enzyme activity regulation.
  • Examples of inorganic ions include hydrogen ions (H+), sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), nitrate ions (NO3-), phosphate ions (PO4 3-) and chloride ions (Cl-).

Hydrogen Ions and pH

  • The concentration of hydrogen ions (H+) in a solution determines its pH level.
  • A low pH indicates a high concentration of hydrogen ions, making the solution acidic. Conversely, a high pH indicates a low concentration of hydrogen ions, making the solution alkaline.
  • Buffer solutions maintain a constant pH, absorbing or releasing H+ ions to balance out any changes in concentration.

Sodium, Potassium and Calcium Ions

  • Sodium ions (Na+) and potassium ions (K+) play essential roles in the process of nerve impulse transmission. They create and maintain the electrical potential across the nerve cell membrane required for the propagation of nerve impulses.
  • Calcium ions (Ca2+) are important for muscle contraction and neurotransmitter release at synapses. They also contribute to the coagulation of blood and bone formation.

Nitrate, Phosphate and Chloride Ions

  • Nitrate ions (NO3-) are crucial for plants, as they are used to make amino acids and thus form the building blocks for proteins.
  • Phosphate ions (PO4 3-) are a vital component of ATP, DNA and phospholipids.
  • Chloride ions (Cl-) help maintain the water balance in an organism and participate in the regulation of pH in the body.

Tests for Ions

  • Various tests can be used to detect the presence of specific inorganic ions. The flame test can identify sodium (yellow), potassium (lilac) and calcium (brick red) ions.
  • The nitrate test involves reducing nitrates to nitrites, which then react to form a red compound if nitrate ions are present.
  • The presence of phosphate ions is confirmed with the molybdate test, producing a blue solution.
  • The chloride test uses silver nitrate solution; if chloride ions are present, a white precipitate of silver chloride forms.