Physical properties of sodium
Property | Description |
State at room temperature and pressure | Solid alkali metal |
Melting point | 97.8°C |
Boiling point | 882.9°C |
Density | Approximately 0.97 g/cm³ |
Appearance | Silvery appearance |
Reactivity in air | Oxidizes rapidly to form greyish sodium oxide |
Hardness | Soft, can be cut with a knife or crushed by fingers |
Thermal, electrical conductivity | Good, it’s also used in nuclear power plants when mixed with potassium |
Chemical properties of sodium.
It has 11 electrons. The outermost shell has only one electron that other elements take away easily. Thus, sodium can react with substances or be oxidized vigorously.
Reaction of sodium with oxygen
Shiny metallic sodium reacts gradually with oxygen to form a thin layer of dull and grayish sodium oxide (Na₂O) on its surface at room temperature.
4Na(s) + O₂(g) → 2Na₂O(s)
If sodium burns in adequate oxygen, it produces a bright yellow flame that leaves sodium peroxide (Na₂O₂) as final product.
2Na(s) + O₂(g) → Na₂O₂(s)
Reaction of sodium with chlorine
It’s so exothermic that explodes in contact with chlorine gas, and the product is table salt or sodium chloride. This’s a classic redox reaction. The highly electronegative chlorine steals one electron from sodium atom during reaction.
2Na(s) + Cl₂(g) → 2NaCl(s)
Reaction of sodium with alcohol
Hydrogen atom in alcohol molecule is displaced by sodium. This reaction isn’t very violent compared to reaction of sodium and water. The most difference is that sodium sinks at bottom and hydrogen bubbles kept rising upward, because it’s denser than alcohol.
2R-OH(l) + 2Na(s) → 2R-O-Na(aq) + H₂(g)
R represents an organic group or alkyl group.
Reaction of sodium with water
When you put a small piece of sodium in a beaker contains water and phenolphthalein, the following phenomenon will be observed by you. The less denser sodium metal will float on water surface. Heat from violent reaction melt metal into a small liquid sphere that moves on water surface as the releasing hydrogen gas. Its size reduces continuously until disappears completely. Phenolphthalein solution becomes pink because of sodium hydroxide.
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
Since it’s one of highly reactive metals, a glass bottle filled with kerosene is used to isolate it from air and water in laboratory.