3 Part One. The Predicate

Covalence

Many compound substances do not have particularly high melting and boiling points, do not conduct electricity when they are molten, and, thus, give no indication o f being ionic. The particles of such compounds are molecules. In these, any bond between two atoms is believed to be a pair o f shared electrons, as it was suggested originally by the American chemist G. N. Lewis. The electrons of such a shared pair occupy a single orbital and spin in opposite directions. Atoms entering such unions are said to cxibit covalence and the bonds thus formed are described as covalcnt.

When two or more atoms share electrons to form molecules, all the electrons of the several atoms involved* become common property and are distributed among energy levels and orbitals characteristic of the molecules. A simpler treatment than this method of molecular orbitals is that of atomic orbitals. By it. cach atom in the molecule is treated as if it controlled all its own electrons except those shared with another atom.

The shared electrons are treated as common to both.The carbon atom has two electrons in its first main energy level and four in its second. To obtain a noblc-gas configuration it would have to loose or gain 4 electrons. Since it can do neither, it approaches the desired goal as nearly as possible by sharing its 4 electrons with atoms that also seek greater stability and will, in turn, share some of their valence electrons with it.

Mashq 3. Matnning asosiy tarkibini bir nechta jumlalarda ko'rsating.

Mashq 4. Matnning rejasini tuzing.

Mashq 5. Jumlalarni o'qing va matn tarkibiga mos kelishini ayting. Agar yo'q bo'lsa, ularni tuzating.

1. Not all compound substances conduct electricity when they are molten. 2. Lewis studied the bond formed by a pair of shared electrons.3. The bond is described as covalcnt if the electrons of a shared pair occupy a single orbital and spin in opposite directions. 4. The method of atomic orbitals is more complex than that of molecular orbitals. 5. The shared electrons are believed to belong to one of the two bounded atoms.6. To obtain a noblc-gas configuration the carbon atom has to loose 4 electrons.

* (he several ato m s involved — несколько участвующих атомов

Mashq 6. Matnda uglerod atomi bilan bog'lanish jarayonida elektronlarning tarqalishi tavsifini toping va ushbu parchani o’zbek tiliga tarjima qiling.