From school or even earlier everyone knows, all around, including also ourselves, consists their atoms – the smallest and indivisible particles. Thanks to ability of atoms to connect with each other, the variety of our world is huge. Ability this atoms of chemical element to form communications with other atoms call element valency.
Instruction
1. The concept of valency entered chemistry in the nineteenth century, then hydrogen atom valency was taken for its unit. Valency of other element can be determined as number of atoms of hydrogen which attaches to itself one atom of other substance. Similar to valency on hydrogen the valency is determined by oxygen which, as a rule, is equal to two and, so allows to determine the valency of other elements in connections with oxygen by simple arithmetic actions. Element valency on oxygen equals to the doubled number of atoms of oxygen which can attach one atom of this element.
2. For determination of valency of an element it is possible to use also a formula. It is known that there is a certain ratio between the element valency, its equivalent mass and molar mass of its atoms. Communication between these qualities is expressed by a formula: Valency = Molar mass of atoms / Equivalent weight. As equivalent weight is that quantity which is necessary for replacement of one of hydrogen or for reaction with one moths of hydrogen, the more molar weight in comparison with weight equivalent, the bigger number of atoms of hydrogen can replace or attach to itself element atom, so that valency is higher.
3. Communication between chemical elements has various nature. It can be covalent communication, ionic, metal. For formation of communication atom needs to have: the electric charge which is not coupled a valent electron, a free valent orbital or not divided couple of valent electrons. Together these features define valence state and valent abilities of atom.
4. Knowing number of electrons of atom which to equally serial number of an element in the Periodic system of elements, being guided by the principles of the smallest energy, Paulie's principle and the rule Hunda it is possible to construct an electronic configuration of atom. These constructions will allow to analyze valency of atom. In all cases, first of all opportunities to form communications due to existence of not coupled valent electrons are implemented, additional valent abilities, such as free orbital or not divided couple of valent electrons, can remain unrealized if on it there is not enough energy. And all aforesaid it is possible to draw a conclusion that it is the simplest to determine atom valency in any connection, and it is much more difficult to find out valent abilities of atoms. However practice will make simple and it.