Q33 of 43 Page 30

Helium atom has 2 electrons in its valence shell but its valency is not 2, Explain.

Atomic number of helium is 2. Its electronic configuration is K-2. The maximum number of electrons K shell can accommodate is 2. It means that its duplet is complete. Helium atom does not have to gain or lose any electron since, its outermost shell is complete with 2 electrons. Hence, the valency of helium atom is zero.


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Complete the Table 4.1 on the basis of information available in the symbols given below

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Fill in the blanks in the following statements

(a) Rutherford’s α-particle scattering experiment led to the discovery of the __________


(b) Isotopes have same _______ but different _______


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(d) The electronic configuration of silicon is ______ and that of sulphur is _____

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