Home
Class 9
CHEMISTRY
(a) The element helium has 2 electrons i...

(a) The element helium has 2 electrons in its valence shell but its valency is not 2. Explain
(b) Choose the isotopes from the following nuclie:
(i)8p+8n,(ii) 8p+9n,(iii) 18p +22n ,(iv)20p+20n

Text Solution

Verified by Experts

(a) The element heliium (He) is a noble gas elements (Z=2) ,It has only one shell (K shell) which can have maximum of two electrons only .It therefore , does not take part in chemical combination and its valecy is zero
(b) Elements (i) and (ii) represent pair of isotopes since they have 8 protons (Atomic no =8)
Promotional Banner

Topper's Solved these Questions

  • STRUCTURE OF ATOM

    DINESH PUBLICATION|Exercise Long Answer Question|20 Videos

  • STRUCTURE OF ATOM

    DINESH PUBLICATION|Exercise Higher order thinking skilll based questions|5 Videos

  • STRUCTURE OF ATOM

    DINESH PUBLICATION|Exercise Very Short Answer Questions|51 Videos

  • MATTER IN OUR SURROUNDINGS

    DINESH PUBLICATION|Exercise (LAQs) Long Answer Questions|5 Videos

Similar Questions

Explore conceptually related problems

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

From the following nuclei, choose the isotopes and isobars : (i) 8p + 8n , (ii) 8p +9n , (iii)18p + 22n , (iv)20p + 20n

If p = 1 (mod 4) then the value of 'p' from the following is (i) 15 (ii)11 (iii)13 (iv)8

Prove the following: P(n,n)=2P(n,n-2)

An element has 2 electrons in K shell, 8 electrons in L shell, 13 electrons in M shell and one electron in N shell. The element is

If n and p are both odd numbers,which of the following is an even number? n+p(ii)n+p+1 (iii) np+2(v)np

A natural atom of an element has 2K,8L, 9M and 2N electrons .The atomic number of element is : The valency of element is

The valency of hydrogen is 1, magnesium, 2 aluminium 3 and carbon 4 . Can you see any connection between the valency of an element and the number of electrons it has in its outermost electron shell ? What would you predict the valencies of helium (He), phosphorus (P), sulphur (S) and neon (Ne) to be ?

DINESH PUBLICATION-STRUCTURE OF ATOM -Short Answer Question
  1. (a) What are canal rays? Who discovered them? What is the charge and m...

    Text Solution

    |

  2. certain particle x has 17 protons 17 electrons and 18 neutrons (i) W...

    Text Solution

    |

  3. (a) The element helium has 2 electrons in its valence shell but its va...

    Text Solution

    |

  4. complete the following table:

    Text Solution

    |

  5. An element is represented as overset(16)underset(8)X.Find: (a) The n...

    Text Solution

    |

  6. The electronic configuration of potassium (K) is 2,8,8,1 instedad of 2...

    Text Solution

    |

  7. Show the electron distribution in magnesium atom and magnesium ion dia...

    Text Solution

    |

  8. The composition of two atoms A and B is given: (a) What are the m...

    Text Solution

    |

  9. (a) what is the relationship between two elements x and y whose atomic...

    Text Solution

    |

  10. write the elctron distrubution of oxygen atom .How many valence elect...

    Text Solution

    |

  11. (a) Why does helium have zero valecy? (b) Name the secientist and h...

    Text Solution

    |

  12. Which observations in scatteing experiment led Rutherford to make the ...

    Text Solution

    |

  13. Write the two postulates of Thomson's model o fan atom .What were the ...

    Text Solution

    |

  14. (a) how many neutrons are present in c-14 isotope of carbon? (b) ho...

    Text Solution

    |

  15. What information do you get from the figure about the atomic number, m...

    Text Solution

    |

  16. In response to a question, a student stated that in an atom, the numbe...

    Text Solution

    |

  17. Calculate the number of neutrons present in the nucleus of an element ...

    Text Solution

    |

  18. Match the names of the Scientists given in Column A with their contrib...

    Text Solution

    |

  19. The atomic number of calcium and argon are 20 and 18 respectively, but...

    Text Solution

    |

  20. Complete the table on the basis of information available in the symbol...

    Text Solution

    |