Main Group Elements: Properties and Oxidation States

Alkaline Metals (ns1)

Alkaline metals have an oxidation number of +1. Features: They are soft metallic elements and react easily, with a low ionization potential that facilitates chemical reactivity. Properties: They are strongly reducing because they are easily oxidized in contact with air. They react with water to form hydroxides.

Alkaline Earth Metals (ns2)

Alkaline earth metals have an oxidation number of +2. Characteristics: They are metallic elements with a greater potential than the previous group. They are not found free in nature but form compounds of an ionic type, except for the beryllium ion which is covalent. Chemically, they oxidize in the air because they are good reducing agents and react with water, giving off hydrogen and forming hydroxides. Unlike alkaline metals, many alkaline earth salts are insoluble in water due to the increased interaction forces that exist.

Boron Group or Earthen Elements (ns2np1)

The earthen elements have oxidation numbers of +3, although gallium and indium can be +2, and thallium +1. Boron is the only element that presents an oxidation state of -3 in hydrides to be more electropositive. All are metals except boron, which has properties of a semimetal; that is, they form covalent compounds. Chemically, they are all reducing agents except boron.

Carbon Group (ns2np2)

The carbonoideos have an electron configuration of ns2np2. The oxidation states are +2 and +4, with the exception of silicon which is only +4. Carbon ranges from -4 to +4. Carbon and silicon present covalent bonds, while others act with a +2 ion or +4 covalent bond. Carbon is a non-metal, silicon and germanium are semiconductors, and tin and lead are metals. The only element that appears free is carbon, which appears in two allotropic forms (the capacity that the same element has to be present in different molecular structures).

Nitrogen Group (ns2np3)

The nitrogenoideos have a configuration of ns2np3. Oxidation numbers are +3 and +5, though nitrogen ranges from -3 to +5. Nitrogen and phosphorus are non-metals, although less electronegative semimetals include arsenic and antimony, while bismuth is a metal. The four allotropic varieties of phosphorus react easily with a very marked reduction character.

Chalcogens (ns2np4)

For chalcogens (ns2np4), the oxidation number is -2 and -1 in peroxides, and +2 with fluoride, while others have -2, +2, +4, and +6. Oxygen, sulfur, and selenium are non-metals, while tellurium and polonium are semimetallic.

Halogens (ns2np5)

For halogens, the oxidation number is -1, although chlorine, bromine, and iodine can act with +1, +3, +5, and +7 when confronted with more electronegative elements. They are non-metals; fluorine is the most energetic oxidant. They react easily with oxidants and are energetic.