Sodium is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation.
Metallic sodium is used mainly for the production of sodium borohydride, sodium azide, indigo, and triphenylphosphine. Employed only in rather specialized applications, only about 100,000 tonnes of metallic sodium are produced annually. Sodium is now produced commercially through the electrolysis of molten sodium chloride.
Protons and Neutrons in Sodium
Sodium is a chemical element with atomic number 11 which means there are 11 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Sodium are 23.
Main Isotopes of Sodium
Its only stable isotope is 23Na. Two radioactive, cosmogenic isotopes are the byproduct of cosmic ray spallation: 22Na has a half-life of 2.6 years and 24Na, a half-life of 15 hours; all other isotopes have a half-life of less than one minute.
Sodium-23 is composed of 11 protons, 12 neutrons, and 11 electrons. Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable 23Na in human blood plasma to 24
Na. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.
Sodium-22 is composed of 11 protons, 11 neutrons, and 11 electrons. odium-22 is a radioactive isotope of sodium, undergoing positron emission to 22Ne with a half-life of 2.605 years. It is also commonly used as a positron source in positron annihilation spectroscopy.
Sodium-24 is composed of 11 protons, 12 neutrons, and 11 electrons. Sodium-24 is one of the most important isotopes. It is radioactive and created from common sodium-23 by neutron bombardment. Therefore its activity accounts for most of the reactor coolants activity when reactor is at full power.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Sodium is 11. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Sodium is [Ne] 3s1.
Possible oxidation states are -1; +1.
Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. Sodium usually forms ionic compounds involving the Na+ cation. Sodium is ordinarily quite reactive with air, and the reactivity is a function of the relative humidity, or water-vapour content of the air. The corrosion of solid sodium by oxygen also is accelerated by the presence of small amounts of impurities in the sodium. In ordinary air, sodium metal reacts to form a sodium hydroxide film, which can rapidly absorb carbon dioxide from the air, forming sodium bicarbonate.
Sodium metal can be easily cut with a knife and is a good conductor of electricity and heat because it has only one electron in its valence shell, resulting in weak metallic bonding and free electrons, which carry energy.
Most Common Compound of Sodium
Salt is mostly sodium chloride, the ionic compound with the formula NaCl, representing equal proportions of sodium and chlorine. Sea salt and freshly mined salt (much of which is sea salt from prehistoric seas) also contain small amounts of trace elements (which in these small amounts are generally good for plant and animal health.
|Number of protons||11|
|Number of neutrons (typical isotopes)||23|
|Number of electrons||11|
|Electron configuration||[Ne] 3s1|
|Oxidation states||-1; +1|
Properties of other elements