Main group element
In chemistry, known as the main groups those groups of the Periodic Table, which belong to the s- and p- block of the periodic table.
The arrangement of the chemical elements in the periodic table was made so that elements with similar properties are each in a group with each other, that is, the columns in the periodic table contain elements with similar chemical properties. The agreement is for the main groups is greatest. The periodic table of the elements is composed of eight main groups. The main group indicates how many electrons are in the outer shell of an atom.
Is particularly clear in the correspondence of the properties for the alkali metals, alkaline earth metals, the halogens and the noble gases:
The elements of the alkali metals are lithium, sodium, potassium, rubidium, cesium and francium. Hydrogen is located in the same main group, but can not be counted among the alkali metals because of its physical and chemical properties. The alkali metals have a low melting temperature react quickly and violently with water ( to form hydrogen gas and the corresponding solution) and oxygen, have low densities, are all flammable and light metals have characteristic flame colorations. The alkali metals are found in nature not elementary, but only in compounds, before. The elemental metals of lithium to potassium is stored in / with petroleum and are soft metals that can be cut. Rubidium and cesium are stored in ampoules and melting largely at hand warmth. Show your salts, such as the elemental metals, in the burner flame characteristic colors.
The alkaline earth metals show a similar behavior as the alkali metals, but are attenuated in all properties. This group includes beryllium, magnesium, calcium, strontium, barium and radium. However, in contrast to the alkali metals to form (with the exception of beryllium and magnesium) sparingly soluble carbonates and sulphates.
The elements of halogens, which are also referred to as salt-forming agents, are fluorine, chlorine, bromine, iodine and astatine. These elements are found in nature only in compounds before and react violently with hydrogen gas ( for acids), metals ( for salts ) and are also colored and harmful to toxic. Since fluorine and chlorine react in the air quite fast and aggressive, one should be careful in experiments with them.
The elements of the noble gases are helium, neon, argon, krypton, xenon and radon. They come in naturally only elementary. The noble gases are odorless, colorless and gaseous. They are present in the air only in small quantities and react not as good as with other substances; a property that they have in common with the noble metals. That's why they are called noble gases.
The fact that the elements of the main groups having similar properties, is related to the structure of the atoms. The main group elements are trying to achieve a noble gas configuration of the electron shell by reactions with other substances. Elements in the same main group must deliver or store the same number of electrons in order to achieve this; therefore result the same properties.