Sodium ion

The sodium ion, Na⁺, is a positively charged ion formed when a sodium atom loses one electron. Its single positive charge and closed electron shell shape its chemical behavior.

Sodium: Sodium is a soft, highly reactive alkali metal with atomic number 11. A neutral sodium atom loses its outermost electron to form Na⁺.
Ionization energy: Ionization energy is the energy required to remove an electron from an atom or ion in the gas phase. Sodium’s first ionization energy quantifies the cost of forming Na⁺ from a gas-phase atom.
Action potential: An action potential is a rapid, temporary change in a cell’s membrane voltage that propagates along excitable cells. Na⁺ influx through voltage-gated channels initiates the rising phase of many neuronal action potentials.
Potassium ion: The potassium ion, K⁺, is a positively charged ion formed when a potassium atom loses one electron. K⁺ has the same charge as Na⁺ but a larger ionic radius and distinct biological roles.
Ion: An ion is an atom or molecule with a net electric charge from losing or gaining electrons. Na⁺ is a monatomic ion formed by electron loss.
Electron configuration: An electron configuration describes how electrons occupy atomic orbitals in an atom or ion. Na⁺ has the same electron configuration as neon after sodium loses its outer electron.
Sodium–potassium pump: The sodium–potassium pump is a membrane protein that uses ATP to move three Na⁺ ions out and two K⁺ ions into a cell. It maintains the transmembrane Na⁺ gradient used in cell physiology.
Lithium ion: The lithium ion, Li⁺, is a positively charged ion formed when a lithium atom loses one electron. Li⁺ shares sodium’s charge but is smaller and more strongly hydrated.
Electron: An electron is a negatively charged subatomic particle found in atoms and involved in chemical bonding. The loss of one electron gives sodium its positive charge.
Hydration shell: A hydration shell is the organized layer of water molecules surrounding a dissolved ion or molecule. Water molecules orient around Na⁺ and stabilize it in aqueous solution.

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