Question

Define octet rule . Write its significance and limitations..??

Answer 1

The octet rulesuccessfully explains the formation of chemical bonds depending upon the nature of the element. It is used to determine stability in atoms. The octet rule helps to figure out how atoms will bond with one another
 It cannot be applied to the nonmetals after silicon in the Periodic Table. These elements can “expand their octet” and have more than eight valence electrons around the central atom. Molecules with an odd number of electrons such as NO and NO₂ cannot satisfy the octet rule.
and much more

Answer 2

The octet rule is a chemical rule of thumbthat reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electron configuration as a noble gas. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium.

The valence electrons can be counted using a Lewis electron dot diagram as shown at the right for carbon dioxide. The electrons shared by the two atoms in a covalent bondare counted twice, once for each atom. In carbon dioxide each oxygen shares four electrons with the central carbon, two (shown in red) from the oxygen itself and two (shown in black) from the carbon. All four of these electrons are counted in both the carbon octet and the oxygen octet.

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