Sodium (Na) is a soft, silvery-white alkali metal, atomic number 11, found in the first column of the periodic table. It is highly reactive, readily engaging in chemical reactions.
Understanding Sodium’s Reactivity
Sodium’s reactivity stems from its electron configuration. It has just one electron in its outermost shell. Atoms tend to achieve a stable electron configuration, and for sodium, losing this single valence electron is much easier than gaining seven more.
When sodium loses this electron, it forms a positively charged ion (Na+), achieving the stable electron configuration of neon. This tendency to donate its electron drives reactions with elements that accept electrons. This electron transfer is fundamental to sodium’s chemical behavior, forming new compounds.
Reaction with Water
Sodium’s most well-known reaction is its vigorous interaction with water. When introduced, it fizzes and often melts into a spherical shape due to the generated heat. This molten ball skitters across the surface, propelled by hydrogen gas. The highly exothermic reaction releases significant heat, which can ignite the hydrogen gas, sometimes causing a flame or explosion.
This reaction forms sodium hydroxide (NaOH), a strong base that dissolves in water, and hydrogen gas (H₂). The liberated heat is sufficient to melt the sodium metal. This demonstrates its intense reactivity.
Reactions with Other Elements
Sodium’s reactivity extends beyond water, encompassing a range of other elements, particularly non-metals. It reacts vigorously with halogens, such as chlorine, to form ionic compounds. For instance, sodium reacts with chlorine gas (Cl₂) to produce sodium chloride (NaCl). This reaction involves sodium donating its single valence electron to chlorine, forming sodium ions (Na+) and chloride ions (Cl-), which are then held together by strong electrostatic forces in a stable crystal lattice.
When exposed to air, sodium metal rapidly loses its shiny appearance and tarnishes. This is due to its reaction with oxygen and moisture, forming compounds like sodium oxide (Na₂O) or sodium hydroxide (NaOH) on its surface. This demonstrates its readiness to react with atmospheric components.
Safe Handling and Storage
Due to its extreme reactivity, pure sodium metal is never found freely in nature, existing instead in compounds like sodium chloride. To prevent reactions with air and moisture, elemental sodium must be stored in specific conditions, typically submerged under an inert liquid, such as mineral oil or kerosene.
Handling sodium requires strict safety precautions due to its fire risk and the corrosive nature of its reaction products. Contact with skin can cause severe burns because sodium reacts with moisture to form corrosive sodium hydroxide. In controlled laboratory or industrial settings, sodium is often handled under an inert gas atmosphere, such as argon, to ensure safety. These measures manage the hazards associated with this highly reactive element.