Electronegativity is an indicator of ability of atom of an element to attract to itself the general electronic couples. Long ago it was established that in case the chemical bond is formed by atoms of different elements, electronic density is always displaced towards one of them to a greater or lesser extent. That atom to which electronic density is attracted in this couple will be considered as electronegative, and another, respectively, as electropositive.
It is required to you
- Mendeleyev's table.
Instruction
1. For definition of electronegativity there are very many methods. For example, there is so-called "Malliken's scale" called in honor of the American scientist who considered electronegativity as the average size of binding energy of valent electrons.
2. There is also "a scale of Polinga" which received the name by name the chemist who was the basis for the concept "electronegativity" binding energy at formation of complex substance from simple initial substances. Electronegativity sizes on this scale lie in the range from 0.7 (alkaline metal of frantion) up to 4.0 (gas-halogen fluorine).
3. In "Olreda-Rokhov's scale" the degree of electronegativity depends on the size of the electrostatic force influencing an external electron.
4. And how to define what element more electronegative and what – less, having only Mendeleyev's table? It is very simple. Remember regularity: than it is above and more to the right in this table there is a chemical element, especially it has electronegative properties. Respectively, the below the element is also more to the left located, the it is more electropositive.
5. The absolute champion on an elektootritsatelnost – halogen fluorine. It is so chemically active element that it has the informal surname long ago "everything cracking". The Poling considered that its electronegativity is equal to 4.0. On the latest specified data, it is equal to 3.98. Concedes to fluorine well familiar oxygen a little – its electronegativity is approximately equal to 3.44. Then there is a gas-halogen chlorine. Slightly less elektrootritsatelen nitrogen. And so on. At the majority of nonmetals the size of electronegativity is approximately equal 2 or is a little higher. Respectively, at the most active – alkaline and alkaline-earth – metals this size fluctuates from 0.7 (frantion) to 1.57 (beryllium).