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The Fundamental Unit of Life
What are the fundamental contributions of E. Rutherford in understanding the structure of atom?
Fundamental contributions of E. Rutherford in understanding the structure of the atom are:
(i) There is a positively charged centre in an atom called the nucleus. Nearly all the mass of an atom resides in the nucleus.
(ii) Most of the mass is concentrated at the nucleus. The electrons revolve around the nucleus in circular paths.
(iii) The size of nucleus is 105 times smaller than the atom.
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What are the limitations of Rutherford model of the atom?
Describe Bohr's model of the atom ?
Compare all the proposed models of an atom given in this chapter.
Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.
Define valency by taking examples of silicon and oxygen.
Explain with examples, (i) Atomic number, (ii) Mass number, (iii) Isotopes, and (iv) Isobars. Give any two uses of isotopes also.
Na+ has completely filled K and L-shells. Explain.
If Z = 3, what would be the valency of the element? Also, name the element.
Composition of the nuclei of two atomic species X and Y are given as under
X Y
Protons = 6 6
Neutrons= 6 6
Give the mass numbers of X and Y. What is the relation between the two species?
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