The element sodium is the 11th element of the Periodic Table. From chemical formula Nasodium is a metal of the first group, the alkali metals. It is a soft metal and is very abundant in nature, being found as an ion in sea salt. Like all alkali metals, it is very reactive, oxidising in the presence of oxygen and reacting violently with water.
Index
SODIUM ATOM
The atom The sodium atom consists of 11 protons and 12 neutrons in the nucleus. Around the nucleus of the sodium atom, 11 electrons circulate, which cover the energy levels (2 electrons in the first level, 8 in the second level and 1 single electron in the last level). This last electron is easily lost, so the chemical charge of sodium when bonded to another element is +1.
PHYSICO-CHEMICAL PROPERTIES OF SODIUM
Atomic mass: 22.98976928(2) u
Density: 968 kg/m3
Atomic radius (calc): 190 pm (Bohr radius)
Group, period, block: 1, 3, s
Name, symbol, number: Hydrogen, H, 1
Ordinary status: Solid
Melting point: 370.87 K (98 °C)
Boiling point: 1156 K (883 °C)
Specific heat: 1230 J/(K-kg)
nºCAS: 7440-23-5
EINECS no: 45.63
SODIUM EXPERIMENTS
Sodium, reacts violently with water, forming the compound
or sodium hydroxide, thus rendering the water highly alkaline, with a ph very high.
Simply dropping a piece of sodium metal into water and watching the reaction is in itself a very colourful chemistry experiment.
SODIUM COMPOUNDS. USES
Sodium forms some of the most widely used chemical compounds, both in industry and in the home. We highlight common salt, NaCl, as one of the sodium compounds.
Sodium chloride. Sodium chloride is the compound that forms the common salt, NaCl, which is made up of a chlorine ion and a sodium ion. This compound is also found in sea salt.
Sodium Polyacrylate. Sodium polyacrylate is a super absorbent polymer used in all those applications where we need to absorb water, e.g. baby nappies, sanitary napkins.
Sodium bicarbonate. Baking soda is a weak base widely used in the home, especially for heartburn. It also has other uses as an anti-grease.
Sodium hydroxide. Sodium hydroxide is one of the strongest bases. It is widely used in industry as a synthesiser of other substances, and in the home as a plunger.
SODIUM IN AGRICULTURE
Sodium is an ever-present element for plants, simply because any water contains small amounts of sodium. Sodium is not one of the essential plant nutrients, but it is used in small amounts, like the micronutrients, as an aid to metabolism and chlorophyll synthesis.
At high doses, sodium in plants is toxic. Similar to micronutrients, sodium at high levels is seen in the form of necrosis or burns at the tips and edges of plants.
Another problem with too high doses of sodium is that sodium competes with potassium, calcium, magnesium and ammonium. If the sodium levels are too high and the doses of the other elements are low or normal, the plant will not be able to differentiate one from the other, it will absorb whatever is in the substrate. Therefore, the plant may not receive sufficient levels of an essential nutrient, which would cause a deficiency (in the tissue).
Therefore, potassium compounds, not sodium compounds, are normally used for agricultural applications. Potassium and sodium have the same chemical valency and can therefore be combined with the same elements. In the case of potassium, it is an essential nutrient for plants and its excess does not cause toxicity.