Showing posts with label Discussions. Show all posts
Showing posts with label Discussions. Show all posts
Sunday, September 7, 2014

What are the Thomson’s model of atom ?

In 1904, Sir J J Thomson proposed the first definite theory as to the internal structure of the atom. According to this theory the atom was assumed to consist of a sphere os uniform distribution of about 10-10 meter positively charge with electrons embedded in it such that the number of electron equal to the number of positive charge and the atom as whole is electrically neutral. This model of atom could not explain the result of gold foil scattering experiment carried out by Rutherford.

What are the defects of Rutherford ‘S model?

According to Rutherford’s model ,an atoms consist of a positive nucleus with the electrons moving around it in circular orbits. However it had been shown by J.C.Maxwell that whenever an electron is subjected to acceleration, it emits radiation and loses energy. As a result of this, its orbit should become smaller and smaller and finally it should drop into the nucleus by following spiral path. This means that atoms would collapse and thus Rutherford’s model failed to explain stability of atoms.Another drawback of the Rutherford’s model is says nothing about the electronic structure of the atoms i.e., how the electron are distributed around the nucleus and what are the energies of these electrons therefore, this model failed to explain he existence of certain definite lines in the hydrogen spectrum.

What is Isomerism?

The phenomenon in which the same molecular formula may exhibit different structure arrangement is called isomerism.Compound that have the same molecule formula but different structure formulae are called isomers(from the Greek word isos+meros, “made of the the same parts”).

What is IUPAC system of Nomenclature?

The international union of pure and applied chemistry has done a commendable job in framing set rules for naming organic compounds.

The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created.

What is octet rule of chemical bonding ?

The tendency for atoms to have eight electron in their outer shell by interacting with other atoms through electron sharing or electron-transfer is known as the octet rule of chemical bonding.

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What is the size of the anion?

When the size of anion is larger, valency electron are less tightly held by its nucleus.Therefore more effectively the cation pulls the valence electron towards its nucleus. This result in more polarized effect. That is, for the same charge of the anion, larger sized anion is more polarized than a smaller sized anion.

Covalent character: LiF< LiCl< LiBr< LiI

 
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